Is the relay REALLY bad? | Understanding HVAC Electrical Concepts
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- čas přidán 4. 07. 2024
- In this video we will be looking at some basic checks to determine if the relay is really bad and if replacing it should be your first choice. I recently had a couple different people approach me talking about bad motors but none of them even used a meter to determine if the motor was bad! Boggles my mind and makes me wonder why spend the money on tools if you aren't going to use them.
For those who haven't gotten their style of troubleshooting, and I guess in some ways their confidence in diagnosing, let me just say this...
REMEMBER THE BASICS!
00:00 Intro
01:21 Relay and Contactor Refresher
07:31 Trane Indoor Fan Relay Checks
18:10 Trane HP Contactor Checks
23:47 1 More Tip!!
Thank you very kindly for your time and sharing the knowledge and different tactics to identify electrical issues.
GREAT content! Thanks for that last part using the jumper for motor controls! 😮👍
Excellent tutorial! Best seen to date.
Thanks, I have been lucky lately finding such a great video that really brings me closer to being confident in my diagnosis of HVAC equiptment.
If you are a new tech it can definitely mess with your confidence. I know guys that have "decades" of experience but troubleshooting switches on relays mess with them really bad for some reason. Learning about troubleshooting switches and being confident in it go a long way. Thanks for commenting and checking it out.
Great Video! Well explained and you touched on two very important subjects
Thanks for making it so easy with relays.
After 12 years in service some time I still overlook or skip relay test and quick to condemn motor or board. Lol
Great video.
Thank you. We can all do it just trying to beat the heat of the summer!
Man your videos are exactly what I’ve been looking for man ! Little things that we over look thanks bro
Thank you.
Thank you so much for your video I'm new in this field and you have a very good teaching ability and very informative. helped me out a lot. Again thank you for your time in making this video.
The coil is the load and the top is the switch. You are correct. Once again thumbs up. Love your videos.
Mr John!
Your videos are very informative. Please continue to upload videos. Thanks again!
Thanks. I took a summer break but will be back soon.
Thanks for sharing your knowledge
I have watched so many videos trying to troubleshoot my blower/ac problem and gotten nowhere. This has been incredibly helpful.
Thank you.
Awesome explanation. Keep those videos coming!! Thank you!!
Thank you.
Thank you 🙏🏻 John for a other great 👍🏻 troubleshooting video can’t wait for the next one keep them coming , stay safe out there
Thanks. The next one might be flounder gigging!
Just replaced a relay on my furnace thanks to this video. Relay was welded shut one of the three heat strips was on constantly. $35 bucks later, good as new. Thank you!! Last year we had the same thing happen and the repair company charged us $500.
Awesome. Now put that extra savings into a retirement fund...or christmas shopping!
Thank you for being a great teacher
Thanks.
Thank you so much for sharing knowledge. I have been trying to educate myself for understanding relays , sequences and troubleshooting for furnace and Ac by watching lots of videos post by many educators for so many years, and your teaching is helping me to understand and learn more for me. I have been watching lots of your videos nowadays and helping me to understand more. Please keep educating and share you knowledge in future too. Thank you
Thanks for watching. I hope to keep you learning.
Same here. Thank you
Thanks for the refresher JJ
Thank you.
Pretty solid video. Thanks
Awesome video thanks John!
Thank you.
Hands-down, one of the best videos I’ve watched on troubleshooting. Your ability to dumb down information for somebody new into the trades is amazing. I’m a 2nd yr apprentice stationary engineer for local 39 in sf.
Thank you. I just try to keep it simple.
Good lesson.
I had a condenser contactor that would close for 8 seconds, then open. Checked for continuity through pressure switches, all okay. Noticed discoloration around the base of the contactor. The contactor coil had just enough resistance to draw the contacts together for 8 seconds, then the resistance would drop, opening the contact points.
I have heard of a few stories like that over the years but never came across it. Thanks for the info.
Thanks for sharing!
Thank you.
Great video
Top of the line simplified troubleshooting
I don't know if it is simplified but that is what I am going for! Thanks.
Nice video man
Thanks for this wonderful video. What can cause the relay to make clicking noise continously. The blower motor works fine. I changed the relay it's still keep clicking
Sounds like it could be the 24v going to the relay coil? It might be getting intermittent voltage and that is clicking the relay switches. I would also make sure the transformer is wired probably and that you are getting 24v out of it. I usually see 26 or 27v. Or maybe something very close to it is clicking instead?
Great video. I like your channel.
appreciate it.
On the power input connection block it is interesting that the machine side has multiple conductors all having stranded wires underneath a single connection screw, without the use of ferrules. The two black wires could use a two wire ferrule, and the three red wires could use a large ferrule to accommodate all three. It may be better for the three red wire connection to use a in-line butt splice with the three wires on one side and a large gauge THHN wire, perhaps 8 AWG or 6 AWG of only about a two inch length, on the other side. The screw block could certainly accommodate an 8 AWG THHN wire.
The Fluke 116 used in the video has a low Z mode on Auto-V which addresses AC ghost voltage. However, many times the Auto-V mode is not needed so AC Volts are used instead like in the video, but not without LoZ. This is one of the reason why I went to a Fluke 289 for HVAC work. The 289 has an AC Volts LoZ range without auto V, which is very helpful in eliminating ghost voltage, and one click away is the AC Volt range with a high input impedance, and next to this is the mV AC Volt range.
awesome video, great content and very clear, im learning a lot from your videos hope i get lucky on the road and some company hires me as a service tech, most of the companies just ask for 3 to 5 years of service experience, but stll refreshing some topics everyday so i dont forget, thanks and if can you give me an advice how to grow more in this trade i will appreciated.
Study at least One hour every day , keep watching CZcams Hvac videos. If no one is hiring, offer your service free. I did with my own tools and van for six months.
Now that guy is my best friend, brother and a mentor. I started 2010 .
READ! Read and study. To me that is the way to getting it and it will still take some time. There was an old Public Service Announcement from back in the day..."the more you know"!
Thank you thank you thank you for this video....I understand now...and I know what I did wrong the other day lol
love your videos didnt know 0 ohms across a relay coil meant its bad.
Thank you. You may find that your meter says "OL" more often than "0" if you have a bad coil in a relay. Either reading when checking resistance in a coil is not good. It has to be a positive number. You should have "0" if checking resistance across a closed switch or maybe just a short wire.
Could either of these be the cause for the fan to continuously run?
thanks for sharing the video. Great work. question? where are the 208 voltage wire (4 wire) on the relay connect to? thanks
I had to remember on that unit...It had a fan relay with two separate switches. One normally open and one normally closed. Two of the wires were high voltage coming in to the switches and the others were leaving the switch going to the fan motor.
Hi, im a new subscriber. I like this video. I've installed this kind of machines, but never had to troubleshoot one. Do you have a video about heaters and how they work and all?
I have one on DC Heat relays, Troubleshooting a Goodman Electric Heat using the hopscotch method, etc. If you look in the video list there are a couple to choose from depending on exactly what you are looking for...and if you don't find it we can try to create it too.
Really well done, what do you recommend for a technician( new) technician when they come up on a wiring diagram and they are having trouble tracing it out(getting overwhelmed with all the wires)
Get a bucket and sit, then slow down and read it. I used to keep a pencil around and would make little dots with numbers on the diagram and plan out my checks for circuits I knew what the voltage was supposed to be. I say that because I was by myself a good bit. If you can get up with a supervisor or someone like that and talk to them that would probably be better. Write down the model/serial numbers and look up diagrams when you get home. Study so you can learn it, then that will become experience in due time. Hope it helps.
U would make a great teacher if you arent already. Great video
Thanks...but teachers work a lot and don't get paid good from what I hear!
Are there any fan relays with a time delay for the heat strips? Would sure be handy to replace hi priced boards or when you cant get one. The fan needs to run for a bit to cool off the heat elements.
I think about relays as more instantaneous but these fan boards nowadays have all that delay built in. I tell the young guys I see that a relay with timing is usually called a sequencer. Goodman used to have a fan sequencer before they used the fan circuit board. I am sure something like it is still out there.
please do one on sequence of operation on RTU, thanks.
I got to get my hands on one but I should have some standard package units coming soon
O L I consider an open lead. That’s why I prefer an analog meter instead of a digital meter. I like to see the needle moving on the meter.
Just checking if you have any videos on teaching ac available great demonstrations
I have some videos on a/c and gauges that are planned but not finished. Sorry. I had a chance to take some vacation and went for it! Thanks for checking the others out and soon I'll be posting some more videos.
I see ya boss lol 😎😎😁✍🏾. Good shit here though John
About time! I got to make sure you ain't forgetting anything when you leave us.
When you go to ohm out a coil on a contact what number do you want to see?
For a 24v coil...maybe 14 to 19 ohms is what I have typically seen for a "known good" one.
what brand / supplier do you like for a 90-340 (for a residential customer, i'm not an HVAC pro)
White Rodgers or Supco are the two that I see the most. They are both reliable in my opinion.
Hai John , i wants ask you a question, i was wondering can I switch the air handle normal transformer to resettable transformer, in case the red power ground , burning the transformer so we just need reset it doesn’t need replaced, because the price are very close??? Thank you 🙏
I prefer a resettable fused transformer over a normal one. You have to protect the 24v power supply. If you don't buy a resettable transformer then at least add a 3 or 5 amp fuse inline to the normal one. I have bought plenty of fuse holders from amazon.
Wow! You read my mind. I was about to comment that you could hook up the motor to direct power to check if the motor was good. And then you threw in that exact thing at the end 😛
I have a question about fan speeds. If you want the heat mode to go faster, is it possible to connect the Black wire via a y jumper to both the Heat and Cool terminals on the fan board? Then you would have only one speed (high) for fan only, cool, or heat. Is this possible to do, or will it cause problems?
If it is a PSC motor then it should work (as long as you only power one speed "winding" at a time. It seems to me that a pot of heat pump fan boards using a PSC motor only power one speed for everything anyway. If it were a furnace board with two distinct relays for heat and cool then you should be able to run a jumper (or re-do the terminal end with two wires in it) from the heat relay to the cool. That should power whatever speed for both modes. Like you said, it shouldn't be a problem.
@@johnjennings487 thanks so much. I have that famous Honeywell universal furnace timer board which has high speed for cool and medium or low for both heat and fan. Low is too slow and on fan mode you barely feel any movement, and on heat mode the flow is not enough and the temp rise is too high.
i really like your videos but i got confused on this one. when you said if power is passing through the switch you should get 208 when its closed with your lead on L2. but if your leads were across the actual switch voltmeter would read 0v correct? i think i just got confused because L2 looks like it should be L1 lol
It all starts to blur together sometimes! With the hopscotch method you will see the full voltage (L1 &L2) as it goes into the switch and if the switch is closed and passing power out you will see it again. On my unit is was 208. Some techs check across the switch itself and by doing that the meter will compare L1 to L1...0 difference. I tell guys that switches and how you check them matter because 0 on your screen does not mean no power, just no difference in the two point you are checking.
What causes a heater not to turn off and heat past the set temperature on the T-stat?
Electric heat??? Probably a bad heat sequencer.
Gas heat??? Maybe a bad t'stat or furnace control board.
Be carefull using continuty on a meter as the be-all-end-all for troubleshooting coils. A lot of meters will use TINY amounts of current in continuity mode, so if you try to test a high load coil (120v and higher) you will still see OL on the meter, doesn't mean the coil is bad, you just didn't have enough juice from your meter to register.
Good point. I try to tell some of my guys to use the continuity on the switching parts and ohms on the coil but may have missed it here. Thanks for bringing it up. You have to know how your tools work...seems like they would put a manual or something with it!!
Bro can you help me with wiring unit
Completely got side tracked at work. What kind of unit do you have?
If the coil on the relay/contactor is getting 24vac and not picking up why continue to test?
For me and the video...just continuing to do the basic checks. Of course in the field, once the coil is gone there is no real need to check because you probably just found the problem.
8:20 What's a "g terminal"?
Just saying the 'G' terminal on thermostat and then going to and through the entire ciruit for 'G' (indoor fan relay coil)
I have a question to ask. With the hvac in my apartment like when you use it to heat up the apartment and it gets to the temperature in setup to shutoff at a giving point it just running and running without a break what does that mean?
For an example I switched it from cool to heat it in got it set to heat at 73 and its feels like 70 inside the apartment and when it finally heats up to same temperature to 73 it seems not to kick off and it's running and running even though it's in automatic.
So, I have been to some apartments/condos that have a heat pump and some that only have electric heat? Do you know what type of unit it is? Either way it doesn't sound like it has enough capacity to heat. It could be low on refrigerant charge if it is a heat pump (and that could be because of a leak somewhere in the system) and if all electric it could just be an undersized heater kit. More info is definitely needed. But if you pay the power bill and rent the apartment, i would definitely let the landlord know. Cheaper and warmer in the end 👍
I was thinking it was a relay switch problem
It's electric furnace
Yes. Could be a few possibles...If it is a multiple heater setup then you very well could have a bad sequencer/relay and are only having one of 2 heaters (or however many) come on and not providing as much heat. Or it may be an open safety for one of the heaters, a bad heating element itself, etc. Most of the time I personally have seen a bad heat sequencer/relay though.
thank you, i always yell at relays and tell them to grow up and be a contactor
I never tried that...maybe throw in a little of kevin harts' "you gonna learn today"
Thankyou for time
Hope it helped somehow.
LOAD THE PARTS CANNON!!! READY, FIRE, AIM! Just kidding. And I think your paying to much for parts! First tool out of the bag should be the meter.
Absolutely. A meter is a the first "must have" and the 2nd is learn to use it.
Heres what i would like to do and pick ur brain 😂 . I have a spit system !!!! The condenser is out side, on the side of the house. 240 single phase .
Now I would like to make the condenser fan to come on first and after about 5 or 10 seconds I would like to have the compressor to come on. What and what kind of durable part would I need to be able to do this.
Without going all out a designing a custom circuit board? 🤔
I guess I would get a White Rodgers 90-380 relay to power the condenser fan and also a ICM102 time delay relay to control the contactor. You are gonna have to jump the 24 Common from the contactor coil and run it to the condenser fan relay coil, but removed the 'Y' signal from the contactor coil.completely and put it on the condenser fan relay coil. This way the fan gets the signal instantly. You will need to run a parallel 'Y' back to the contactor coil but it will go through the time delay relay to give you whatever time delay you wanted. You would need a little bit of wire and a terminal or two but it shouldn't be too bad to do nor take up much room with the parts. Hope you can follow my thought process! I am sure there are other ways also. If nothing else it might help you get started.
@@johnjennings487
Thank u
Will try it. But I was thinking more of after the contactor or too the compressor . Letting the contactor pull in , for both the condenser fan and compressor but breaking the power to the compressor after the contactor, this way the contactor pull in when there a call and the fan starts but the compressor will not till the timer or what ever , makes. And starts the compressor.
@carlossaenz4075 i tried to think of something like that but the compressor is the larger load and it might be easier to just split the loads with a separate relay. But...with electrical there is always another way!
That wasn't a technician was apprentice, you pay what you hire. A poor technician or a great technician.
In a lot of cases I can agree with that but an apprentice has to start somewhere and I think it takes a minute to build the confidence in hvac knowledge they need for the field.
It's not that complicated. This ain't complicated. It's simple linear troubleshooting.
Absolutley agree that it isn't complicated...if you know what troubleshooting is. But how many troubleshooters out there are replacing something from memory rather using a meter?
Very boring.
I'll work on it.
Correct me if i am wrong. We have to put a jumper from 2 to 5 and the wire for the lower speed to 6? Cause this cannot be used for heat strip unless the amperage is comparable to the heat strip. Best to use a 90340. Correct?. I appreciate your respond. I seen this use to replace Goodman circuit boards or boards similar to the one used by Goodman.
I had to take another look at that relay before I got back to you. This relay is a 24v coil, 1 N.O., 1 N.C. setup. The 90340 is a DPDT relay and the N.O. and N.C. share a COM terminal.( I figure you know that already but just for someone reading). With the original relay having 2 seperate switches you could theoretically wire it to run a heat speed and a cool speed on the PSC motor. By jumping the #2 and #5 terminals you basically make it a COM like the 90340 relay has got on it. The COM side of the switch is where to put the blower speed wire. Goodman and others do this but it just means you only run one speed for both heat and cool modes.
And that relay is not one to use for heat strips! Too much amp draw like you said.
I use my meter every time, i belive any technician that assume that a part is bad without using the multimeter shouldn't be in this business. I am retired, only have my right arm, but i always use the multimeter.
I think that is how they come up with the "part changer" name...no meter no worries. Just change a part!