Why Do Gas Furnace Control Boards Fail?
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- čas přidán 9. 07. 2024
- Why do gas furnace control boards fail? Another one of my hvac training videos which deals with a common furnace repair. As an hvac apprentice or experienced journeyman, you have to know why control boards are not working. Control or circuit board failure can be frustrating because they tend to go out intermittently. ESD or static electricity will cause a furnace control board to fail over time. Electronics fail over time, but other damage caused by a power outage, power surge, or another voltage spike like someone taking a power pole out. A blown fuse can prevent the circuit board from working too. So really a myriad of things can happen to cause a gas furnace control board to fail.
Greg Fox HVAC training videos on You Tube come Fox Family Heating and Air in Sacramento in 2020.
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I like whole house surge suppressors as a way to way to extend the service life of electronics. One of the factors is when lightning hits a powerline within a mile of your location. Ultrahigh frequency components can easily travel distances and jump utility and control transformers to damage semiconductors. I do believe there are solutions through superior manufacturer’s design (including comm circuit isolation, on board voltage protection and solid state switching) but the easiest retrofits may be whole house surge suppressors. Proper single point ground rods in house wiring can help as well and is sometimes compromised when someone separately earth grounds a subpanel or outside unit.
Very good information! See its experts like you who are an asset to this channel.
Indeed. There are many, many electronic devices in the home now, especially with the advent of Smart TVs and the Internet of Things. And spikes and surges can happen for many reasons. But keep in mind surge suppressors do need to be replaced on a regular basis. They will lose capability over time. The maximum lifetime of most surge suppressor power strips is something like 10 years.
Heater was on the fritz, HVAC tech said control board needed to be replaced and that it was replaced just a few years ago so I'd probably have to replace the entire furnace. Quoted 6700 for a new furnace and 1300 to fix it. Ordered the new board off of repairclinic for $60 and fixed it in 20 minutes. I realize they gotta make money but the markup is just insane. Had a lot of bad power surges this past summer, thanks for explaining this. My furnace is back to working fine.
As an electrical engineer, there are only 3 reasons boards fail - poor design (there was no worst case operation analysis done when choosing or sizing the parts), cheap parts (like Chinese relays instead of name brand relays, and Chinese capacitors vs name brand capacitors), and crappy assembly (poor soldering during assembly) and no vibration mitigation (no selastic holding the larger parts to the board leading to cracked solder joints from vibration). These boards are all repairable - I've repaired many furnace boards. Usually when I repair them, I use better parts, and they last forever, and the repair parts cost less than $10 (usually much less). At $350 or more for a board that contains $20 worth of parts, the boards are designed to fail on purpose because they make a lot of markup selling replacements. Your car uses a lot more complicated electronics, and they're exposed to much harsher conditions (voltage spikes from the ignition system, vibration, extreme temperatures, water, salt, dust etc), yet they fail relatively infrequently compared to simple furnace boards. Automotive electronics have much higher standards of both design and assembly. There's no excuse for furnace boards not lasting the life of the furnace, other than that they only pay enough to get the people that barely passed their engineering degree to design them, and or they shave pennies off the parts cost by choosing the worst quality parts available.
Thanks for the info! I have an intermittent gas valve relay operation. Tapped the relay and it started working again. Not sure if it's a cracked solder joint or not, as it's a fairly old control board. Where would you recommend I get a replacement one? It's a 24 v relay TIANBO HJR-2FA-SV-Z
@@jum5238 If you tap the relay and it works again, it could be a bad solder joint, or it could be the contacts in the relay are pitted from arcing, and the relay is just worn out. You can reflow all the joints on the relay, as this is basically a free and quick check. Also reflow the spade connector (or pins of the multi pin connector if that's how it connects) where the gas valve actually attaches to the board. Any connectors are subject to cracked joints too from the repeated vibration of the cables connected to the board when the furnace is running. Best place to get replacement relays is Digikey or Mouser. You're not going to find the exact brand, but most relays have a similar footprint, so should be somewhat interchangeable. You want to look for the same coil voltage and same or higher current capacity on the high current side. If it's for the gas valve, you probably don't need a lot of current capacity. Check the datasheet of the parts your looking at for the pin layout, and check the spacing and layout of the pins of the existing relay on the board. If the board has any electrolytic capacitors (round thing that stands up off the board), I'd replace those too while you're ordering parts. They dry out after a while, and when they dry out, the control board will stop working (the DC voltage that runs the microprocessor will be 'bumpy' enough to continually reset the processor, then everything stops working). If you posted some pictures of the board somewhere, I could maybe help further.
Ahh yah most boards today are wave soldered with no lead making it easier to have dissimilar metal corrosion and dry cracked solder half the time the relay pin looses solder and goes open it’s so sad people don’t teach themselves how to repair rather than replace ..02 cents worth of solder can save you hundreds and some techs will try to sell you a new furnace then you are out thousands.
I appreciate everything about this comment so very much.
i have a hvac gas furnace control board. Whenever i tap the relay it starts to work again. i changed the control board and after fitting the second board (bought a used one from ebay), it worked very well for 15hrs and then again furnace went down. Tapping the relay is again making it to perform well. what could be the problem here as its two different boards but same tapping is getting the furnace to work again? thank you in advance
Wow...that was probably the most clear and easy to understand explanation I have ever heard....you're an asset to the community...
Thanks so much! I appreciate you watching too!
Thank you for this video. I am searching for answers the day after my 25 yr old Erie boss series had a zone relay meld, then ignite the plywood mounting board. The fire then burned to the 2 nearby studs. Only because I was home, I ran to the basement and extinguished the fames before the fire department arrived. Your explanation was spot on and very comprehensive. I am puzzled why NEC or some building codes do not require boiler controls to a metal plate vs commonly used wood. Maybe that is too simplistic. Thanks.
Thank you for this video I'm just starting out. This was super helpful.
Jason
North Carolina.
My experience so far is that if the other parts(pressure switch, gas valve, flame sensor...)works one week and then they don't the next week for a period of a few months, the control board is failing. It would look normal until it eventually fry like the one on the video.
As a tech thank you for these videos brother
Recently had light switches replaced also a ceiling fan which blowed out maybe crossed wires. Would this be an impact on my control board as now I need a new board as no heat or air conditioning? Let me know. Thank you.
Voltage drop from Xfmr hot, through tstat can cause IFC to not read a closed pressure switch. Can add a switch to connect Xfmr hot directly to heat demand fed by the Tstat head demand lead. The dropped voltage will close the switch and the full Xfmr power will pass directly to the board.
Tanks for the great info!
You got it 👍
my 3 amp fuse blew out, i replace it only to have the cap next to it catch on fire.
im replacing the board and transformer..
anything else i should check?
I have re-soldered many fractured solder connections on both connectors and relays. I have never had a re-solder joint that failed.
I've started packing a 'jeweler's Loop' as part of my gear. It allows me to get that view 'up close' I need to examine the integrity of a connection or a contact's surface. Once you get past the voltage readings then moving to the board/component integrity helps me determine future approaches when faced with that brand of a component. P.S.Resistor vs Transistor, they look different.
Thanks. I made the edit to the video. My bad! Lol
I did replace a board control at my RV, only work for a few hours, hopefully I 😢just get a defective device,
Ugh, I've got one that is becoming extremely irritating. Trane S9V2 cir board randomly shuts down blower and the led readout display always goes out with it. Suspected power issues, this is a brand new furnace. Issue been persisting for 6 months now, electricians say all their circuits are good. We get out there and the system board is always down, blower isn't functioning and coil has frozen up despite the low pressure switch on the condenser. I thought maybe the contactor was randomly intermittently sticking closed but I tested the shit out that thing and couldn't get it to stick closed once. I suspect by evidence found today that something is causing the board to shut down which Is consequently causing the blower to shut down but is still allowing 24v signal to tstat and condenser. Thought it was surges as I've seen this several times before but not to this degree where it's shorting a board randomly every few days. I suspect maybe the generator is causing voltage fluctuation beyond units capabilities or maybe Hz is fluctuating too far out of range. Plan to return with 2 boards in couple days and run through entire system with trane tech support and hopefully we can resolve this headache. Will update when we resolve problem and maybe it will help someone else down the road if they experience similar issues.
Acidic condensate drain water gets into the boards from leaky tubing. Bad run capacitor on circulator fans ruin relays.
I had the cool tab fried on a board. Do you think faulty blower motors can cause boards to fail??
I had a circuit board catch fire I replaced the first one and second one did it again as soon as I turned power on. How come?
GREAT VID
Thanks!
I have an ADP ceiling mounted garage heater. I suspect the control board to be bad as it is not sending power for the burner ignition stage. The board is readily available online. Is this a replacement that can easily be handled by the homeowner. I would classify my skill level as advanced handyman. Thank you in advance for your earliest response.
I have 10 year old Burnham Alpine 080 and my LCD burnt out. It should receive 5V but the voltage on the harness shows around 32V. The voltage on transformer is 24V. The boiler keeps working but we are flying blind. I did replace the control board (pricey) and the LCD (pricey). The LCD lasted few seconds and burnt out. Where is the problem? Can you point me in the right direction? Link, so I can read more about it? Any suggestions appreciated
Why? The solder side ofva arcoaire board is burnt?
my hvac relay is unstable. i have to tap on it frequently to get it working? i have changed the control board but the second board also is having the same issue? is this a control board issue or relay issue or furnace issue? kindly advice and thanks in advance
Good job!
Thanks. First comment of 2021. And it was a good one!
@@foxfamilyheatingandaircond4696 Happy New year!
Ive had an abnormally high amount of boards that lost flame sense after PGE cut power numerous times last sept. And im still getting calls from customers that have second homes and just making it back up here to the mountains and starting their furnaces for the first time. I must have changed out 25 boards in 1 1/2 months.
Holy cow. That's a lot of boards!
What model amd brand
Yep! Mine just did the same thing, a 15 y/o Winchester (made by York) but I wasn't sure if it was the board or the flame sensor rod itself, so I cleaned and inspected the sensor, seemed fine, but....flame was still being lost anywhere from 4-6 times each heating cycle. Then, I happened to notice the board wasn't giving any codes at all, where it had initially. Also, the green "all systems go" light was no longer coming on, so to me, it was a no-brainer....didn't even check it, just replaced it, and now it's running perfectly.
This just happened to us in Texas. This video was very timely and informative.
Hi very interesting video !
Is there way to wire ac unit without control board
Please could ou make video showing how thank you
With the cost of control boards within reason, why not just replace it? There are low voltage to high voltage relays and signals that have to happen. You would have to make these connections manually every time you would want the system on or off.
The answer to your question is yes. In the old days----there were no boards. The first furnace I had I think it was a Bryant and it was all mechanically controlled and powered by a 24 V. transformer in combinations of bi-metal wire wound heat switches and a heat-sensitive twist tube control switch that fit in the heat exchanger. Worked great and rarely caused trouble.
I just changed mine on a 4 year old furnace. Armstrong Air.
I just purchased a new control board about 2 months ago it was working fine today I turned on my air conditioner and now the control board has when out again
I replaced mine the ignitor part wasn't kicking on and it works good now. Is it normal that everything looks normal on the old board? I'm wondering if it was just dirty
The board was ready faulty I just expected to see a stain on the board
Yeah it's not necessary to see any damage. It could be internal to a part on the board. Happens all the time. Even tiny fractures can make it happen. Very rigid boards with rigid solder connections. Glad you're running again
Solder side is burnt why?
I have E112 error code on a Lennox furnace
It say ground faults
This error locked all the furnace features
For me all the control board that failed and I replaced caused by a bad capacitor .
I found a bad board in an ICP package unit. Now my cousin has a bad board in their 30 year old Goodman package unit.
Very good video but I'm trying to find out if a failed control board can cause a gas furnace to cycle off and on I have replaced the flame sensor but it will run one time then the next day it will cycle on and off so I'm thinking it might be a fail control board
Yes it could be the board but it could be other things too. I know, furnaces can be frustrating to diagnose. We went back to one lady's house three times trying to find the right diagnosis. Ugggh
@@foxfamilyheatingandaircond4696 yea I got another flame sensor on order so I'm try that before I get a circuit board
Customer had a no heat issue and a tech replaced the gas valve one month before. Now no heat again. 24 volts measured at valve. On close inspection found a fractured and burnt solder joint on board.. still making some connectivity to deliver voltage but not required current to open valve.
Absolutely. And that is why I tell people furnace season can be frustrating for customers because there are so many intermittent issues going on with the board, gas valve, pressure switches, etc.
Pressing on the relay makes my furnace work, so I'm guessing it's the bad part. Unfortunately, it appears the relay is obsolete.
how did you fix this? did you change the entire board?
@@anil1011anil1011 yes, the entire board. Now, it works fine.
Mine blew from excess humidity. 3 year old natural gas 100000 but carrier
They’re very finicky to power fluctuations. And the fact that there’s too much crap going on with a board.
Agreed! Thanks for the info!
I have had to replace those control boards every 2 to 4 years
Have you found a relatively cheap UNIVERSAL mother/circuit board you can buy, or do you go strictly by the model#? In other words, I can't find an EXACT match with the furnace model I have to a mother/circuit board, so I'm looking for a Universal one(or one that is supposed to work on multiple furnace brands/types....I'm guessing as long as all the parts/connectors are in the same place, I can use ANY mother board sold---does that sound right to you?....What is your experience with buying these boards, as far as going outside the box to save a few bucks? thanks...
Bring back the old relays
Float switches shorted tstat wire bad capacitor bad blower motor power surge loose tstat wire at low voltage terminal bad 24v transformer bad contactor at condenser bad tstat or my favorite, mis-wire the system!
DIY amateur .. found bad transformer .. replaced and initially tried air conditioner thru thermostat and it worked. Switched tstat to heat and transformer burnt up.. going to replace control board but concerned that it could be another component causing the problem and that I could damage the new control board .. any advice?
It could be a limit switch shorting to the heat exchanger. I've seen it before - furnace runs fine, then as it heats up, the limit switch bends from thermal expansion, and shorts against the heat exchanger - can take out the transformer, the board, and the thermostat itself. It comes down to shitty design (or designed to fail on purpose).
@@gorak9000 thanks .. have new control board installed and this board has a fuse that blows immediately when heat comes on - also it had a test function that cycled thru a
the main components of the heat with no problem .. since heat has not been required and a/c works haven't gone to next step of trouble shooting apparent short between the heat terminal and common ground . I am assuming that the fuse kept the fault from damaging the new board and I just need to isolate the components and check them for short with my meter .. fingers crossed I can figure it out though at 70 yrs old I seem to make mistakes more regularly
The problem is that the board costs damn near as much as the system
Replacing a board is doable by most homeowners and boards are available on e-bay or Amazon. They start at around $100 dollars or so. I just put one in my trane and I think I paid $113.00 for it and 20 minutes to install. Get the new board and then swap the wires from the old to the new board,, one at a time.
You misspoke and kept saying "transistor" when you meant "resistor." which is what you kept showing in the pictures. A transistor by itself is a little semiconductor with three leads, often in a pea-sized plastic case. Now they come thousands or millions in a package called microcomputers. They are the components that are extremely sensitive to electrostatic discharge.
I've found a common failure on circuit boards is water. It will allows currents where they aren't supposed to go. Spilling coke or coffee on a laptop is the worse. So, take little leaks seriously, they only get bigger.
I appreciate the correction 😊
I made the change! Thanks for the heads up!
water is bad, condensate water is very bad! it often has large amount of contaminates from the indoor air.