How to Repair a Frozen Air Conditioner | Ask This Old House
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- čas přidán 1. 06. 2016
- Plumbing and heating expert Richard Trethewey shows how to prevent ice buildup from shutting down an air-conditioning system. (See below for steps.)
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Richard troubleshoots an air conditioning coil that freezes up with use. Richard replaced a 4-ton air conditioner with a more appropriately sized 3-ton air conditioner.
Steps for How to Repair a Frozen Air Conditioner:
1. Clean or replace the return-air filter to ensure it's not obstructing the flow of fresh air to the air conditioner.
2. Confirm that the size of the air-conditioning unit can accommodate the diameter and number of cool-air ducts.
3. Remove the metal access panel to expose the evaporator coil.
4. Check the size of the outdoor condenser unit. Typically one ton of cooling is needed for every 500 to 600 square feet of living space.
5. If the condenser is too big for the house, it can cause ice to form on the evaporator coils and shut down the system.
6. Pump out and collect the refrigerant from the existing too-large condenser.
7. Disconnect the old condenser and cart it away.
8. Install a new appropriate-size condenser.
9. Connect the new condenser to the existing electrical power supply and refrigerant lines.
10. Remove the old evaporator coil and replace it with a new coil that matches the tonnage rating of the new condenser.
11. Reconnect the ductwork and seal the new evaporator cabinet at top and bottom with sheet metal strips and foil tape.
12. Braze new copper connections to the refrigerant lines.
13. Insulate the suction line.
14. Connect PVC pipe to the condensate drain and then attach the pipe to a pump.
15. Run flexible tubing from the pump to a drain.
16. If necessary, add refrigerant to the new system.
17. Turn on the air conditioner to ensure it's operating properly.
Expert assistance on this project was provided by Papalia Plumbing [papaliaplumbing.com/] and Air Purchases [www.airpurchases.com/].
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How to Repair a Frozen Air Conditioner | Ask This Old House
/ thisoldhouse - Jak na to + styl
"Hey my lines are frozen"
"Let's check your air filter..measure your ducts..yep just like I thought. You need a new unit."
😆
Hahahahhahahhahaa
Right?!?!? That’s ballsy even for residential techs.
@@davidcerino1145 I'm honestly thinking about doing this next frozen line I come to, just to see their face. "It's only three years old!" "Well you're about two years overdue for a new one."
Steven Douglas
😂
About 2yrs overdue! Ha!
Check this out. I bought a new home and over the years I noticed that the upstairs never really cooled down (get to about 78F the lowest on the hottest days)while the unit ran all day! Over the years had 3 different HVAC guys look at it ( coolant level was good, filters always changed, coil good etc) correct ton unit for space and still warm upstairs. I just figured the design of house with warm air going up the vaulted ceilings and dumping into the 2nd floor. After 8 years of this, I finally had enough and went up a half ton with all new coil and condenser. Well hell, little more than half way through the tear down guy said here is your problem. All the damn paperwork ( warranty, owners manual plastic bag etc ) was trapped and up against my blower motor blocking probably 70% of the air flow!!!😤 they never removed it and would not had noticed it unless I tore down the blower box. Good news it nice and cool upstairs now but a $5000 lesson and dumb ass installers.
🤣
wow
installed by this guy?
Wow
Funny
Purchased: August 2023 - still works GREAT!I czcams.com/users/postUgkxxsUnXhGsSJLim_XnMHyQK0u3XVaW-CGn live in a studio and during the summer it gets scorching hot - really old building with no ac units. I can’t express how EASY it was to install. This unit has been a life savior during the summer and some days during other seasons where it can still be a bit warm at night. In this small place is my friend, a husky, poodle mix and myself. We need AC - lolI don’t use the dehumidifier option - I’m not sure if it will leak in my house, since I did not install the small draining hose that came with it. May look into it late but I don’t worry about much humidity in the apartment. I don’t understand why the negative reviews since all things mentioned, I personally did not find issues with. Definitely worth it!
This problem was addressed in my HVAC class several years back. Most techs wanna jump out and throw the gauges on it first thing. My instructor DRILLED into us "Airflow,Airflow,Airflow!" Here is what I was taught. 1.Check the filter and make sure it's new/clean (if no filter is present, the coils may be clogged) 2. Check the fans both in the evaporator and the condenser and make sure they are moving air. 3. Check the Thermostatic Expansion Valve and make sure it's not hunting, and that it's functioning properly. 4. Check your refrigerant level. And if there is a leak, fix it. Don't top it off! However I do agree that oversizing is a problem. It's actually better the system be a bit undersized than oversized If a contractor is going to do an install like this and doesn't do the manual j calculations, run them off!
I know in architecture classes we were taught that you want the units "undersized" as incapable of fully heating or cooling the extreme hottest or coldest the area sees as the last few days is a big jump in system size. But this isn't my specialty and I may be remembering wrong, but that is my recollection at least
Kenneth the
if the superheat/subcool are checked, whether it's a txv or orifice can tell if the low pressure is caused by low airflow or a leak or restriction.
Tip: Even if the filter is there, check the pressure drop across your evaporator coil and total external static across the blower inlet to furnace discharge.
Your pressure total from the RA to furnace discharge should ideally be about 0.8"-1.0". Check your manual for total external static pressure. (A dual port manometer is great. Use the "-" port on the inlet side of the blower and the "+" port on the discharge side of the furnace.)
The static pressure drop across a wet evaporator coil should be about 0.2" wc usually. A greater pressure drop indicates a restriction and you should visually examine it.
1300 square ft home changes 4 to 3 lol. A 2 ton is the correct answer.
"My AC is freezing up. What should I do?"
"Spend $6,000 and let us install a new condensor and A coil!"
ike fun - was the ad hominem really necessary?
TruthSurge... LMAO. I still remember you getting your ass handed to you by Sye Ten Bruggencate
shortage of refrigerant. check for leakage
@@jhuh1758 - More than likely, or else loss of superheat from a faulty TXV overfeeding the coil.
My AC had the same problem, but in addition the outside unit would continue to run even when the thermostat inside turned off the inside circulation fan. I had to manually pull the disconnect circuit breaker outside to shut it off. Turned out that the contactor relay switch on the outside unit had gotten stuck in the closed position. I was able to unstick the contactor by prodding it with a screwdriver, but it was very pitted, so replaced it.
me as an Hvac technician, I say that all he was supposed to do was check the refrigeration pressure, and increase the size of his return duct
And how big a blower do you need to force enough air over a coil designed for a 2 1/2 ton TXV to become [barely] servicable to a 4 ton outside unit? You wouldn't be able to sleep for the noise I would imagine, and would have to worry about the air filter getting sucked into the blower housing constantly. Yes you can fit a square peg into a round hole with a big enough hammer, but its just wrong.
@@flinch622 no excuse please
Maybe change that filter to a regular one also for more airflow
Yep, 100%
Question: Do you change your filter?
Answer: all the time.
lol...I’ve never heard that before.
Bufford Baxter Lmaooooooo
Depending on the size of the home determines how often the filter needs to be changed
RV on The single yes. All the time
I change mine every 3 months at most, sometimes monthly. However lol, people I ask.. like neighbors are like "Wait you're supposed to change it?" These people bought their homes 15 years ago.
@@mikecoulter5243 what? 😳
Had a friend who shut the air vents off to two unused bedrooms in his house , reasoning he would save money. Wound up freezing up evap. Hvac was designed for specific amount of air flow across evap.
I learned a new thing about the history of "ton" in air conditioning!
My AC unit was freezing up...and I placed a small FAN in front of the intake vent (where the filter is)...turned the fan on...and *no more freeze ups*!!! Works like a charm
What does that do?
@@larsonfamilyhouse it forces more air through the intake.
It’s only a coincidence that works. That fan is likely doing nothing. There’s lots of reasons for that
*Easy to assemble **Fastly.Cool*
They forgot to film the part when he gets a 10,000 dollar bill
They probably paid for it.
10g for a 3 ton? I’m 4 grand. Where do u live I’m moving
@Kaptain Kid sadly
right !! that ac didnt need changing..its something else
Such a scam
After watching numerous HVAC videos on youtube, I spotted one thing straight away that could have solved his problem: his return air was undersized. For a 4 ton system, that return air was way too small. No wonder it iced up. His system also had a TXV so that should have been looked at as well. It was hard to determine how the sensing bulb was placed due to the camera angle.
Not only that, the refrigerant levels should have been checked once the A coil was thawed out. Like others have said, there are so many things wrong with this video.
Homeowner said the system ran for 1 hour and then iced up. I'm guessing it was a bit low on refrigerant, TXV was probably running wide open and the A coil gradually iced up.
His new A coil has a TXV as well. A lot of HVAC technicians don't like them due to them being problematic.
16" round is about 1,250cfm at .1 static. If we are using 400cfm per tonn that would be 1,600cfm for a 4ton traditional split. Ain't no way that return duct was 16" lol. Looked more like an 10", hard to tell from the camera angle.
Regardless the problem was his duct work being under sized, having an over sized system by 1tonn will not freeze your evap, it will cause short cycling depending upon how much it is over sized. Short cycling will lead a shorter compressor life due to overheating. This in bad situations will get the oil inside the compressor too hot and will not lubricate the compressor properly which will die soon. The low pressure gas that has been super heated is what usually cools the compressor in residential applications.
Did anybody notice he explained the refrigerant flow backwards when he opened up the coil. This whole video is just wrong.
AS General no it isn't everyone knows the refrigerant gets metered heading back to the compressor
return duct work is massively undersized. A complete miss by these 2 and it's still undersized for the 3T unit. You can run 3 ton cond thru a 4T coil all day long. The 10- 12 inch return needs to be 18- 20 or equivalent in square duct and replace the 1 inch filter with a 4 inch filter set up. They'll be back the 3 t unit will be freezing up.I've been in HVACR since 1985.
I have lost all respect for This Old House as an institution.
its not an institution lmao
It hurt me physically to watch this.
Good job running those pipes right i front of the service pannel. Allways makes changeing an expansion valve more fun.
LOL, customer should've been handed a jar of vaseline with the invoice. 😂😂
😂
That's no kidding lol
That's a good one
LMAO!....so true.....
Big Texas Lmaooooooo
Good idea. Remove an oversized unit and replace it with an oversized unit. Good deal!
I bet it's a air flow issue rather then it being under charged. it has a txv so it should of helped prevent freezing and constant superheat. I can't believe they didn't check the charge during initial testing or even check static pressure or cfm/ airflow. Did you notice when he was explaining the evap coil he said the liquid line was "leaving the evap coil and suctio line bringing in the the refrigerant"!! I like to know what size blower that furnace has. it also the worst duct system install I've seen in a while...that return us way too small. they also had the old coil improperly installed because of it being a larger size then the furnacr. the manufacturer specifics how a over sized coil can be mounted on a furnace. No checking delta T with the AC runnung, not checking the superheat and txv subcooling, no airflow testing, massive amounts of Flex duct supplies... " how do we know the system is charged correctly"..The system, like a lost all comes charged for 15ft of pipe, but that's not checking the charge. what was the superheat and subcooling with the new system? this guy probably needs a crappg ez flow filter to drop static pressure..anything to help with air flow...still that return is pitiful and should have been probably addressed. I though the this old house guy would have said something about the horrendous installation...what a shame for this old house. No heat load calculations...determining size by Sq footage!! LOL, even this old house isn't immune to hacks. if this old house wanted to really impress viewers they would have used a imanifold to should how poorly the system was operating and all the specs the system is running far out of! I could of figured this out with my digicools, minivan anemometer, my old school dwyer magnehilic, dual temp monitor with delta t measurement. You never NEED to have a matching evap coil and can always size up one size to increase humidity removal and increase efficiency. we have situatations 4 ton condensers with 5 ton evaporation coils to meet ashre combinations and correspondence effeciency. I'm glad heat load Calc are required for permit application for replacement systems! That knock half of the local hacks0 m outfits out of business because of their lack of education and fines for not doing their job properly. I'm 25 and have my hvacr master license. I did grow up in the business, full disclosure, and am the tech side of the company and troubleshooting the people who decided the lowest bidder was a good idea because they don't understand they aren't buying a car or appliance. They are buying a service that require engineering of hvac system, and duct system, to ensure the outcome will not turn out to be hacked like this type of job which is a embarrassment to ALL competent HVAC techs and they should be mad these people are in business. the only reason this homeowner didn't complain is because they didn't pay for the new system!!
Not that we would know accurately but def say about a 2 ton unit would have done it
@@NytefogNJ I know nothing about HVAC ducting specs but what if they simply "ported" vents and intakes into the basement for more air volume???
My thoughts exactly. This is like a 1200 sq ft house in temperate middle USA, where it probably gets to like 82 on a hot July day. What it probably needs is all new duct work and likely a 2 to 3 ton unit.
Just In credible not necessarily. I have a 3 ton unit in hot and humid South Carolina with 1800 square feet, and it cools okay. On a 100 F day it just maintains, but it’s fine. This small house in the middle of the temperate USA should need less. A 3 ton unit with proper duct work would blast them out of there.
Need a new paint job on the house??? better build a new one
Hahahahaha nice one
Lol. He would have been better off doing the house addition to cover the extra ton.
🤭 😝 😆 🤣🤣🤣
Could have opened a window to control freeze-up. Haha🤣
Omg, great way to explain how crazy this was!!! Kudos
I had this as an issue. My Coil kept freezing over. So, I just had a team come out and replace the entire system: condensor, coil, furnace. Also replaced another condensor, and did some other repairs. Now my house is freezing cold! So happy!
Wow this homeowner got bent over in over charges and equipment that was fine.
Would not be the case if the right unit was installed to begin with
I've repaired & installed many split(central) AC systems over the years. The problem was more than likely LOW refrigerant. Sometimes you can have a faulty expansion valve.
you'd think they would check the charge first, maybe they didn't show that
Low refrigerant
Faulty blower motor
Dirty coil
Dirty air filter
Gabriel Martinez restriction, bad TXV, clogged Orpheus , capillary tube or filter gone bad . Many more
electronicsNmore .?.
Since I've been doing the air condition for 22 years if I was to come up to this unit or house and see these problems other than wasting all that time measuring ducks and everything else you said we could have just looked inside the a coil and found a core and more than likely just packed with dirt just used to be cleaned and then check the freon level after that also first thing I noticed was that return duct being so small if you don't get enough air back to the system it will freeze you increase the return it you could have fixed it or he could have even better turned up the speed on the blower and and that would have saved him the 10,000 to $15,000 wasted money of replacing the unit for a smaller unit
You forgot to mention the most common area of a unit freezing up, is the underside of the evap coil. Rake and use coil cleaner and spray it clean. There's usually mold and dust buildup that gets past the filter (most people don't change them as often as they say they do). It can get so thick that no air can move through the unit. Another thing is checking freon pressure. Low pressure (or air in the line) will freeze a unit up just like this. Check the condenser fan is actually turning on (spin with a twig and if it starts, it's the capacitor). Leaves and grass buildup around the condenser can also cause this. Hope this helps someone, no need to rush out and spend 5 to 6 grand on a brand new unit.
Yes that was my 1st thought
A condenser fan, faulty motor or twig, dirty condenser, or air in the lines will not cause freezing. In fact, a dirty condenser will actually raise pressure
Yelp he just overlooked it all together.. 😅 He just made a lot of money off of him..
Most residential AC condensers use old technology developed by Mr. Carrier about 100 years ago. Many Asian AC condensers now use more and more inverter technology, some of them are capable to work with a wide range of loads. You won't need to worry about being oversized or undersized. They work even if they are 200% of the required tonnage.
This guy has all kind of sales plaques and trophies on his wall 😂🤣
How to repair? More like how to replace...
Yes
Or how to "UP Charge!!"
He can sell the old unit and either break even or make money.
@@VinylToVideo the contractor is like "oh, don't worry, I'll get rid of the old one for you". lol
@@bigroblee Exactly. My grandparents just replaced their 20 or 30 year old hot water tank. When the old one was removed it was realized it was just fine and probably could have lasted another 30 years. Of course it wasn't scrapped; it was taken and probably resold and they didn't get any money for it.
Richard: your AC system is too big.
Homeowner: so what do we do now?
Richard: Well, take this hose and start sucking out the refrigerant. You can spit it into that bucket over there while I go chip some of that ice off and have a drink
lol. Yes replacing the unit will definitely stop it from freezing over. If it’s someone else’s money, bring it on!
AC system worked great for 15 years, starts freezing up, yep the entire system installed was too large and everything has to be replaced. :rolleyes:
the AC was 4 years old when this was filmed and likely never worked right from the getgo. That ductwork is WAY too small for a 4 ton, especially that return. Looks like 16" which is 25% of the minimum you need or worse 14" which isn't even half. The contractor who installed the 4 ton was obviously a hack and had no idea what they were doing. You can't put a 4 ton in ductwork sized for 2 ton of air. Not to mention theres a damper system so if you are shutting off half the system, you now have 4 ton of air going through ductwork that can support 1 ton of air. and there is no bypass damper either which isn't going to help with freezing.
It was just low on freon.
@@gangisspawn1 Nobody uses freon anymore.
@@Egleu1 So after the freon ban all r-22 units just disappeared or were replaced? Fool
Yeah good thing everyone can afford to just replace an entire ac system.🤦 Especially if the system worked great for that long.
Wow. This guy doesn't really know much about the A/C does he. He just told the home owner that refrigerant runs backwards
I noticed that too.
I started laughing as soon as I saw that.
Matthew Martinez he's just a general carpenter or handy man not an hvac tech
Yes Matthew, I just saw this video and the guy is showing refrigerant flow backwards through the metering device .
I was confused about that the liquid line carries the refrigerant into the metering device
That 14" return duct will only supply 1000 CFM at best, but more likely 800 CFM after the twists, turns, and filter. 800 CFM is only enough air to feed a 2 ton unit, and it's probably drawing from the floor or low on a wall where return air temperatures will be coldest, further exacerbating low coil temperatures - which forces the TXV the close more to maintain the same superheat, lowering suction pressures below freezing.
The problem isn't "too big for the house." The problem is "too big for the ductwork" which was obviously sized for the much lower CFM of a gas furnace. Without sufficient airflow, evaporator saturation temperatures will be too low and freeze up week happen again.
Thank God someone else gets it. Yeah 1000 CFM at .1 static, but at .05, which is what I use for supplies it is only like 700 CFM.
Being 4 ton he needs like 1600 CFM, so that's at least double the return.
The host has no idea how air conditioning works indicating cold flows from the suction line, lol. It's actually the high-pressure, subcooled, liquid line that hits the restriction causing a huge pressure and directly proportional saturated temperature drop. Would need a PT chart or to just look at where the gauge needle intersects that refrigerant's markings, but this would require they actually explain something to the viewers.
While it could certainly be low on refrigerant, that TXV is probably holding back to hold a constant superheat and not burnup the compressor.
Even with a 3 Ton system, they should have improved the airflow a bit then ran some airflow static pressure tests... but you know this.
Additionally, they are full of crap about not needing to charge the system. While it does come charged from the factory, that assumes a perfect lineset length and that they read the directions for proper line sizes. Either way any competent tech will run the system under load for a while then check the pressures, saturated temperatures, and then compare those to actual temperatures to verify the superheat and subcooling... and adjust that system's charge to the proper subcooling. Much of the time the factories mess up how much refrigerant they put in new systems, and even when they get it right, it is rare to hit spot on with a proper charge.
return duct work is massively undersized. A complete miss by these 2 and it's still undersized for the 3T unit. You can run 3 ton cond thru a 4T coil all day long. The 10- 12 inch return needs to be 18- 20 or equivalentin square duct and replace the 1 inch filter with a 4 inch filter set up. They'll be back the 3 t unit will be freezing up.
Seriously I couldn't have said this any better. This guy is a shitty sales man. That home owner got punked
Yes, When I was 1st year apprentice in 1969, I learned that with a forced air system the most important aspects were that it needed to suck and blow.
EightiesTV do you even english bro
"My AC is freezing up"
"Well that's because you have a much bigger unit than you need, so instead of using a superheat sensor to do a bypass shutoff on the compressor and keep the fan blowing to reduce your condensate freeze build up, we're just going to replace your entire unit with a much smaller one, giving you slower cooling for the entire house, making you waste more money than you need to."
"Genius idea Richard, let's do it!"
This is the answer I was looking for! Hahah
Exactly! If your car has an engine that's too powerful for speed limit, lift up the throttle! Why can't HVAC system incorporate simple sensors like you described and throttle back?
I'm a layman and I knew that there had to be something like what you mentioned.
and how would a properly sized air conditioner be a negative? who cares if its smaller? you would rather have an oversized air conditioner that's uncomfortable with humidity problems? and an oversized air conditioner wastes more money than a properly sized one - there are tons of studies proving this. Plus in your scenario, you are running the fan more often, which is also using a lot more energy as that heater uses a PSC not an ECM motor. If you don't want to change the system, why not just correct the ductwork? That return is obviously too small at 14-16inch. Not to mention there's a damper system which is cutting the supply in half or worse - and there's no bypass damper. With undersized ductwork & oversized equipment, the superheat is going to be way too high and you are going to get liquid flooding back to the compressor rather than vapor, causing damage over time.
@@wshtb The compressors found in most homes are designed to either run or not run, that's the issue of why they can't be throttled. But there are air conditioners that can throttle themselves back / speed up... they are called Variable Speed Compressors and they can run anywhere between 30% and 100% capacity. They are commonly found on Ductless Mini-Splits and higher SEER Split Systems. It is a lot more complex, expensive, and temperamental though... but they can reach much higher efficiency and comfort levels.
Just call... "THIS OLD LIEN AGAINST MY EXISTING MORTGAGE TO REPLACE MY AC"
an oversized unit doesn't freeze up that quick, most of the time it's a refrigerant leak. makes for good TV though, some hvac companies love more business doing poor troubleshooting jobs.
I know, right?
He never checked to see if the evap coil was dirty or checked the charge.
oversized units don't freeze, dirty coils do, and he didnt check it.
or probably the controller doesn't work properly. the compressor should turn off automatically when it reached the set temperature.
@@bradowen8862 - Stick with your day job dude. Frozen coil = no airflow. No airflow = no cooling inside house. No cooling inside house = thermostat never reaches its set point.
@@bradowen8862 You would have to add a discharge temperature control, or a freeze stat on the evaporator coil. They don’t usually come with the unit, and are a band aid, not the solution.
Never run the refrigeration lines across the front of the a-coil cabinet! You want clear access to the face of the coil to be able to clean or inspect. They very easily could have crossed over at plenum height and then dropped down to the piping connections on the correct side of the cabinet.
Our house's old A/C was too oversized and we never had any freezing problems. The old unit was a 5,200 BTU/5 Tonne unit and it was replaced with that very same condenser seen in this video which the seller of the new equipment said was just the right size for our house.
How to fix your freezing ac coils? Rip the whole thing out and buy a new one. Gee, thanks...
They "FIXED" the unit for $10000!! I am astonished how many likes this video has!! Is this for real??? Did you notice the recovery jug is brand new and the recovery machine too?
That old condenser was almost brand new. That sucks.
Looks like an idiot homeowner bought it online. See this all the time, they buy way too big of a unit
Looks like an idiot homeowner bought it online. See this all the time, they buy way too big of a unit
Boo hoo...for every "idiot" there are many more who do the job right and save a TON of money. No pun intended. HVAC isn't rocket science especially with the great online content that is now available.
Absolutely false. Like socialism. All good on paper, and no connection to reality.
that money should used for a new addition lol.
The AC is under charged or leaking somewhat, low on refrigerant, so in evaporator the refrigerant temperature is too low, that cause freezing. replacement can fix the problem too.
Sheng Liwei -or possible dirty evap coil. This video is wrong.. check the easy stuff first
So basically if my car has a check engine light with a mis-fire, I just buy a new car?
No just fix the timing dumbshit
Would have been nice if they would have address the return air ducting at the same time.
As soon as he said “that sounds heavy” he knew he had a new unit sold
“Sharp edges sharp edges” gloves man gloves!!!! Haha they help some I’ve cut my hands so many freaking times especially the days I don’t wear em 😂😂💯
Cut 12in hole in Supply & return plenum. Condition the basement. Save $$$
Wrong
Wrong
Then you still have to add refrigerant :)
By doing that you have just now added a space to your determined in size unit. It could work out in your favor, only if you are oversized.
Overall though: that would only decrease the effeciency of your system. Best thing and easiest thing to do is clean the system and up the blower motor speed.
@@DW-vl2wi wrong
Another fine hack job my friends!!!!
The 12" or 14" round return should have been ripped out and completely redone. Return air is choked down. This results in insufficient air flow and can freeze the coil. I doubt changing out the condensing unit and coil cured the problem.
Wow what a hack nice return on that install definitely a air flow issue a good tech would have taken a static pressure and would have determined high static as well as being over sized lol, must have been a home depot special install
Will that suction and liquid line block access to the evap coil
I don't the round return duct connection to filter rack. A box should have been install so that the air from the round pipe flows thru the whole air filter and not just the small round area.
I agree the existing unit was prolly oversized, BUT not enough to cause a frozen coil.. An oversized unit could and sometimes does cause mold issues... Frozen coil or line set could be a VERY dirty coil, a bad capacitor, motor or both, or a leak in the refrigerant lines...and sometimes an expansion valve can cause some minor freezing
That system probably did not have enough return air even for 3 ton let alone 4 ton. With that said, Richard lets spending the budget on HVAC stuff.
Subscribed! You definitely have a great knowledge around these concepts, Sir. Thank you!
Very solid video! Thanks for the clear presentation and the little remark questions to remind/educate us. Thank you!
Well same thing happened to me and I changed my filter. Now it's fine. A $8 fix.
I'd never put money into a smaller unit!
@precision Brown, 🙊
wow I was chocked to see the repair was to replace the whole unit. for a frosting over coil its either low on refrigerant, txv inlet screen dirty, "A" coil dirty, dirty filter, or something is up with the indoor fan motor.
harley davidson if it was low on refrigerant I would think he would show a leak, but yea I’m leaning on something being wrong with the fan motor
Justin credible your the only one who said “expert” and it shows in the comments that everyone else agrees with you smh 😒
Yup. lol
I’m surprised he didn’t recommend an air scrubber to go with it,
The comments are why I watch these episodes 🤣🤣
Nice video. Thanks for the info. But I believe if I'm not mistaken liquid refrigerant enters through the metering device and then through the evaporator as opposed to the way it was explained.
The homeowner did not state whether he had this freezing problem ever since the unit was installed. The outdoor unit looked pretty new to me. Also, if a low charge (leak) was a possibility, why didn't Richard mention it ?
I heard that if it's low on refrigerant that will be the reason for the freezing problem.
This is a national show that's highly viewed. I'm sure the AC companies LOVED this episode! Why not buy a shiny brand new unit that makes those companies thousands of dollars instead of showing a better fix that doesn't make them anything. I'm sure that had something to do with it ;)
Tommy Taylor
I suppose credibility isn't a priority of the show. Al Gore and Bill Nye the dumba$$ Guy didn't have any.
return duct work is massively undersized. A complete miss by these 2 and it's still undersized for the 3T unit. You can run 3 ton cond thru a 4T coil all day long. The 10- 12 inch return needs to be 18- 20 or equivalent in square duct and replace the 1 inch filter with a 4 inch filter set up. They'll be back the 3 t unit will be freezing up.I've been in HVACR since 1985.
and then they'll sell the dumbass a 2T unit.
How the hell can you make *any* determination without hooking up pressure gauges?!? Regardless of oversize, if it's a new unit and is freezing, it probably has a leak from poor installation.
thechosendude exactly, I'll said the same!!
Homeowner alert!
If you know so much about HVAC work, why are you watching this video big guy?
@@gunner6903 because bud in the HVAC business you will never be a master of the trade every year there is something to learn....some new technology that's why my field always keeps me on my toes....also that's why I'm always watching videos novice or professional I need to see what ALL people are doing in my field....
TRUE MAN OR IT NEEDS A BYPASS DAMPER SO THE COOL AIR DONT COMING BACK TO THE RETURN AGAIN
The (MAIN) problem is lack of RETURN AIR.
The RA duct is too small.
Yes the unit might not be sized right but the duct work is just as important to handle the PROPER airflow.
Dude! When the guy from This Old House suggests putting an addition on your house, you say yes!
Man so glad I found this channel. You guys give way too much good info. Keep up the great work! New first time home owner benefiting from all this knowledge.
In my area: "Yup, the systems good but we need to build a new house."
I’m building a new house and I’m *_so_* happy with the HVAC design company we’re working with... an ERV (energy recovery ventilation) for fresh air, dehumidifier unit (SW Florida, you can drink the air 9 months of the year) and a VRF (variable refrigerant flow) compressor system (the _”compressor system”_ has a proper name I’m forgetting... let’s say _”the unit”)_ all properly sized and balanced for the airtight SIP (structural insulated panel) construction I’m using. Add the 8.1kW solar PV array, two PowerWalls and some other renewable tech and I’ll be thrilled to stop paying *_stupid_* amounts of money to cool the 100+ year old house I’m replacing... there aren’t enough fans in the world to run a pressure test on the old house, it’s basically a sieve. btw, I added the acronym meanings for the few folk who’d watch this video and not know what an ERV and such is... I’m sure most of you do but it’s cool tech most folk don’t think of (having a totally airtight house shell is usually not an issue !!), and videos like these make me so happy I’m doing it !!!
Indoor coil doesn't have to be the same as the outdoor unit. You could of done a 3 ton outdoor unit with a 4 ton indoor coil for better efficiency.
Wouldn’t that essentially cause the service factor of the compressor to be compromised?
When I say tons you say, "That sounds heavy". Take 3, and quiet on the set, "ACTION!".
ha
There was not enough return air on this system and the furnace part of the system only had a blower capable of handling 3 tons of air flow through the coil max. In this case it makes sense why the coil was freezing. Usually a freezing coil means you are low on Refrigerant. So the proper solution would have been to increase the return size and downsize the system. The 3 ton system they put in is only a half ton over sized for the home at most, but they did not fix the return air problem.
How would you increase the return size?
@@rogar61 A return can be cut into the other side of the furnace and ducting can be run to the space that needs it. Normally the furnace has its main return on one of the sides. You can use both sides. The cheapest is to cut in a filter frame on the side of the furnace not being used if its in a open space in a basement. Keep the door to the basement open or cut in a return grill upstairs that is open to the basement. My cheaper not necessarily approved method is to take the blower door off, defeat the door switch with strong tape and the proper size filter sits where the blower door was. Does not work with all furnaces.
@@grawey77 So you would have one return with ducts going to various parts of the house and another "return" that is essentially a hole cut into another side of the furnace that would pull in air from the basement or whichever room it was located?
@@rogar61 This only works when the furnace is in an open basement and not closed off. Inside doors in houses are typically not air tight. A return grill open to the basement either in the sidewall or the floor would provide air from upstairs. Best located in an open area in your home, like a main living space. You have to remember you are just adding return to increase the air available for efficiency. The system will already have returns in the bedrooms if its an average home. You can of course duct in another return from the other side of the furnace to a main living space. This is what professionals would probably want you to do at more expense. I actually sleep in my basement because I am a 3rd shifter. Having a good size return in the basement helps dehumidify and condition the space. I do have supply ducts in my basement too.
@@grawey77 That makes sense. Thanks.
I've been in the field for a few weeks and a lot of the new condensors i've been putting in are double in size i put in a 4 /12 ton from a 2 ton and a 5 ton unit. The model number tells the size of the unit? 6030??
Lol. I love the way he talks to the homeowner
Have you tried WD-40?
That system was sized for heat, not cooling. return was too small
Muito bom! 💪🏼
I had a new condenser and air handler put in last May in a condo my son lives in. The condo is in northern Florida and the company recommended I go from 2.5 to 3.5 ton. The company put in a 3 ton condensor 14 SEER and 3.5 ton air handler. I was charged for a 3.5 ton 15 seer system. The company that installed this heat pump said with the match they did, even though the condensor was 3 ton 14 seer, the match up with the 3.5 ton air handler made it a 3.5 ton 15 seer system. I don't know if I got scammed or not.
How to repair? Replace the whole damn thing. Jeez thanks that was really uninformative.
Richard did not have clue what is going on. there are many possibilities. He did not even put gauges or take temperatures.useless video
Forget replacing, sell the house and move to Montana, AC there is optional...!
We could argue this all day long the bottom line is it was oversized and needed to be replaced. Now I find that most likely of the coil icing up is air flow if you looked at that coil it was iced from the bottom to the top in less than an hour low on charge won't ice the whole coil in less than a hour from top to bottom. It is easy to determine this charge to air flow problem take the suction line temperature if it's lower than 50 degrees air flow problem above 70 degrees charge problem.
Damn ike. You're making me think that you're the only real Tech in the comment section. Thanks for all you're insight.
Thank you for your time. Question: my AC/Heat Pump is freezing up around the indoor unit coil. No AC at all. Thermostat and inside fan are working, filter and A-frame are clean, drain plug is NOT clogged. Outside fan and compressor are working too; outside coils also clean. I haven't measure capacitance, but assume dual capacitor is good since compressor and fan both run. I haven't check for low refrigerant yet (R-410A). What could possibly be the problem? Would the defrost control board have anything to do here (it's spring time and only inside is freezing). Thank you much in advance!
Juan Diaz.
1/ triple check airflow, return and supply.
2/ check indoor fan capacitor/s uF.
3/ temp setting too low, cooling during coolish weather; can cause ice.
4/ thermostat, running endlessly not cutting out.
5/ incorrect gas charge. HVAC tech: If leak can't be found. Weigh gas out/ weigh in.
*defrost control board has the purpose of de-icing outdoor coil during heating cycle so not likely the fault . HTH
Does this old house have Q and Answers. On rooftop coolers , my cooler and furnace are hooked to the same ductwork. Will heat go through the cooler. If so is it ok to put a cap on after I take cooler down.
So this unit has been freezing up since it was install, wrong! The txv should keep this from freezing no matter the size of the unit. this is low on freon or txv is bad.
I think the same but this guy need pay bill on the back of other's 😄
Don't need p trap it's positive pressure system need straight pipe with air opening
It's a wonder that he didn't also have a buddy ready to build an addition onto the house. I don't even remember seeing them check if the refrigerant level is low.. just replace everything because it cost the most to do!
Some of the explanation of the refrigerant circuit and the hand gestures used to indicate flow were not correct, but I was glad to see that Richard brought in a local Pro to do the job. Most of the time, you do not get the near perfect fit when you exchange cased indoor coils on a change out. Homeowners, this is a job to NOT take on yourself.
The longer i looked at the A/C install the more i feel like im having a stroke
a low freon charge will do the same problem. also, blocked acoil, defective blower motor and clogged capillary tubes. let's see, I only did this for 10 years
I guess the right title for this vid is “how to replace AC unit”. Solving evaporator coil freeze is another task dude!
Evaporator coil freeze is usually due to one of the following reasons:
1- Less Freon charge: This produces low pressure thus low temp (goes sub freeze point), the solution, check for Freon leaks and increase the charge to the right level.
2- Indoor air blockage:
Make sure nothing blocks the air flow, probably:
A: paper stuck against the evaporator coil.
B: dirty return air filter!
C: indoor fan not running: either due to defected indoor fan or defected controls like fan relay!
3- Bad low-pressure cut-out:
Make sure the low-pressure cut-out is working properly, since freeze occurs when compressor is not cut out on time!
4- Bad thermostat sensor:
Make sure thermostat sensor is functioning well and cutting off the compressor at the correct set temperature and not lower than that.
5- Oversized ACCU for this AHU:
Make sure outdoor unit cooling capacity equals/matches the indoor. If it’s more capacity then it might flood the evaporator with subcooled Freon causing temp goes sub-freeze.
6- Evaporator is partially frozen!
This is an indication of wrongful brazed tubes inside! That’s a factory defect, you probably need to replace the evaporator coil.
According to my experience, frozen evaporator is 95% due to either low Freon charge or faulty low-pressure cut-off.
Thanks
Personally would have used S strips on the plenum, and tried not to use any couplings on the line set. Less joints is always a good thing. Cool video though always like seeing how other installers work.
So much wrong going on here. Wow.
He never even checked the charge! Precharged for 25' my ass. I would have kicked him out of my house leaving that plenum looking like he used a can opener on it. I can't believe they posted this video. I would fire an employee for a job like that.
handyman hack job....I've only been doing HVAC for a year and I could do much better.
The problem is the undersized return duct, it's maybe a 10 or 12 inch, had to be 18 at least for 4 tons, 16 for 3, or the equivalent in square duct. Replacing the 1 nch filter set up with at least a 2 " preferably for would help a lot as 1 inch filters have alot of static pressure drop. . I've been in HVACR since 1985, I knew what the problem was as soon as I saw the unit, this guy missed it, he must not have a ductulator. They'll be back with the unit still freezing up, and you can run 3 tons thru a 4 ton coil, many high efficiency jobs require that. They should have redine the return duct 1st before any equipment replacements, you will see a lot of this in the field.
Such a non specific comment...almost meaningless, in fact.
after watching this video, I had the feeling the poor guy got scammed again.
Installation properly done good job
Hey guy I am a Ac technician and own my own company for years and the way you explained that refrigeration cycle is very wrong it does not get sucked back by the discharge line the refrigerant goes back to the condenser by the suction line which is the fat line at the TXV goes to the coil and distribute cold liquid not vapor
First he described the Freon in the wrong direction and it doesn't come from the condenser cold it comes back hot and changes temp when it passes through the TXV. And over sizing wont cause it to freeze. It'll cycle off and on to fast and not pull the moisture out of the air like its designed too. So you'll have low temp and high humidity.
I noticed that too that he was described the flow of freon backwards.
Exactly... If this were me helping this guy, first thing I would do is add at least one more 14" metal return, and then a bit more to increase it to hopefully 1600 CFM at .05 static. Right now he is getting maybe 700 CFM per my duculator... That's almost enough air for a 2 ton system!
The guy described everything backwards about the refrigerant flow... agreed. While it may also be low on charge, as you know the TXV controls the refrigerant and superheat such that this type of system should be charged to the proper subcooling Then check its superheat is in range and its coil temp should be like 40F to 45F maintained by the TXV to never freeze up.
They might want to kick the blower motor up a bit too. I don't know. Either way it is a classic bad install, and the new unit still never addressed the return airflow problems though it reduced the air hunger to 400 CFM less.... It still needs 1200 CFM at 3 tons and has at most 1000 CFM even at .1. At .07 it is still lacking 300 CFM and at .05 static it is lacking 500 CFM. Basically, they only half fixed the freezeup issue.
The new installer was not even competent enough to mention they still MUST check the charge! I very rarely if ever have the factory charge end up being perfect/ideal.
"We need to see what we can do for you today" (then a new concrete pad shows up out of nowhere)
Exactly the AC nightmare bill nobody wants! However, a Nice install and information video.
i have a 2000 sq ft house and i have 2,5 tonne unit why is he using 3 tonne unt. Good video I like Richard from TOH - he's knowledgeable.
Can't even imagine how expensive this mistake would be!
Well the mistake of installing the incorrect sized unit!
The only mistake here is getting the wrong guy to solve your problem. He couldn't even explain the proper workings of a refrigerant system.
Didn't bother to check the pressures to diagnose potentially clogged expansion valves. Likely did a terrible installation job which will guarantee the thing chokes and freezes again.
never thought having too much ac power would be a bad thing
I need an explanation.. I don't get it either!
An AC should also dehumidify the air. A properly sized unit will run for a while, taking out the humidly, and cooling the room. If its too large, it will cool very quickly, but not have enough time to dehumidify before turning off.
An oversize unit also cycles much faster. Turns on, then quickly turns off. Cycles are what tend to wear out the unit the most, so a properly sized unit that runs longer will actually last longer. A smaller unit will also cost less an energy, and cost less to by.
because you roughly need about 400cfm per ton and it was a 4ton.
then you gotta also size the duct for a 4 ton ac that can handle the volume of air needed.
thats why always make sure you have the filter clean. dirty filters restrict airflow.
An oversized ac would short cycle and not remove a lot of humidity.
The balls they have to leave this video up lmao. Thanks for letting me share this episode of this old hack
ok, first let me say that I think Ask this Old House is a great resource and I learn from it every day. Having said that now you are in my domain and I would like to make a few comments. I agree that looking at air flow should always be first. Unless the system is designed for it I would question the use of a pleated filter. A total static pressure test should be done on every system. I will assume that before you put a 3ton system in that house that you knew exactly what the air system could handle and what the load of the house was. I don't see best practices being done here with the removal of the old components. I know this is basically a video for the homeowner and not an installer guide and some of the install procedures are presumed done correctly but it would be very helpful for homeowners watching this to have a check list of best practices. I am not here to provide that list now, but I would have worn gloves, cleaned that copper before cutting, reamed all cut copper and flowed nitrogen while brazing that copper pipe. Mentioned leak testing with dry nitrogen and a proper vacuum afterwards, the installation of a new filter drier always any time a system is opened and finally a check of proper superheat and sub cooling before assuming that the system is within length requirements for the refrigerant charge that came with the condenser. I can't tell you how many times I have gone back to help someone on a new install and found the charge was short of only ounces of refrigerant. The needed refrigerant improved overall operation and efficiency.
He should have checked inside the A-coil for clogging, especially if the owner has pets as pet hair getting past the filter.
exactly my thought. I just cleaned the underside of my A evaporator coil. It was caked with a lint like covering. That was the cause of my AC freezing over. There wasn't even a mention that they checked it before going through the expense of replacement.
This is true, clean the coil .. but cleaning the A coil wouldn't be as interesting or as profitable as selling the dude a new system. LoL sbt
Anthony Browning where do u clean under the coil? this is what happened last time my ac froze. it stopped working and started dripping water. tech cleaned the coil and everything works fine for a while then I believe it got clogged again and is now doing the same thing.
Ben Woods When you pull the outer cover and look at the end of the a-coil, there will be a triangle plate held in place by sheet metal screws. Remove those screws and the plate. My cover plate is kinda hard to wiggle out from behind the copper lines, be careful. Then you can look at the under side of the coils on both sides. Mine is a triple pass for the freon, so when cleaning mechanically I can really only clean half a pass. After getting all the crap off there, you might try using coil cleaner or foam to help clear the rest of the coil. Good luck.
Anthony Browning thanks
Richard is an expert in HVAC systems. Far outsmarts 99.9% of others out there.
No he is not. He is a plumber
Without a doubt, you don't see the presumptuous of this comment. You are not a technician, so you're not in the industry. You have no experienced eye to evaluate Richard's level of expertise, and just as importantly, how his skills stack up to "the others" out there. To a guy who really knows this stuff, it's apparent Richard is in over his head in HVAC. To a the CZcams bleachers, however, Richard is an HVAC God. He might be a plumber God; he might be. But he's not an HVAC pro. Far from it.
Making it look easy like always
My lines also freezing up and got it turned off for over a day now thawing them out . I think my coils are on top of furnace in that closet space . How can I get to them with those lines connected too ? I'd like to check and clean the coils since filter was definitely filthy .