Our Air Conditioner as well as heater will not come on. I have checked the disconnect outside, the breakers and still nothing. I had someone helping me earlier but he opted out. Can anyone else help?
Type of HVAC: Air Conditioner
Thanks for giving me the opportunity to help! I'm sorry to hear you are having issues. Can you tell me this? What happens when you put your thermostat in the fan "on" position? Does the inside blower come on? This will help us first determine if we have 24 volt control power and also whether or not the thermostat is working. If the blower does come on, but not the outside unit, next check to see if the contactor is pulled in on the outside unit. You will need to remove a cover on the side of the unit right about where all the wiring comes in.Tim H41023.8058122685
No the fan does not come on. I took the thermostat off and tried jumping the green and red wires (as per the instructions from the last tech) and nothing then as well.
Next you need to check in the air handler or Furnace (working without any model numbers here) for a small 3 amp fuse that may be blown. It will look similar to this and be in by or on the main control board.Tim H41023.8152162037
Lennox model #g4ouh-36a-070-07Here is a link to a pic of the unit in the attic. Where would the fuse be? Is it in the cover to the right?
No, it is in the bottom door of the furnace on the circuit board. Or if furnace lays on it's side, the next door over.Tim H41023.8389773495
If this is blown, try replacing it (you can pick some up at any automotive store) and see if it starts. If not, or if it blows again, then we need to check for other issues.
More than 20 years experience.
Ok, I visually inspected the fuse, as well as tested the fuse for continuity with my voltmeter, it tested good.
Accidentally accepted, what do I do?
It's no problem. We will continue to work on it. Do you have access to a voltmeter? If so, put the setting on volts AC and open the door where you found the fuse. Push in the blower door switch located near the top of the door. Test across R to C (or common) terminals on the board. We're looking for 24 volts here. If 24 volts, next set the thermostat to cooling and check across C (or common) to the Y terminal. Again we should see 24 volts. Let me know what you find.
ok the lowest a/c volts setting on my ohm meter is 200 (not sure if this matters) but when I pushed in the door switch and went across the r to c terminals I only got 1 volt. I didn't bother to do the second test since we didn't get 24 volts.
Locate two terminals on the board that are marked XFMR-H and XFMR-N. Push the blower door switch in, and check across these. We're looking for 24 volts. If no voltage, check across Line-H and Line-N. Across these two we should have 120 volts. Let me know what you find on all these readings. Make SURE that the voltmeter is set to volts AC, not DC.
Ok, I'm going to upload a few pics of the circuit board. I couldn't find the transformer terminals, however I did find the line h and n (hot and neutral?) and there is 120 volts there. sorry it takes me so long, it is in the back of my attic, and I have to crawl to it, and then it's on its side.http://imgur.com/a/In9bO
You can use any of the whites on the board as a neutral. The XFMR-H should be right below the Line-H terminal. If you test across any of the neutrals to XFMR-H and get no voltage, the transformer is bad and will need replacement. This is unusual for the transformer to go out without blowing the 3 amp fuse first, but guess it can happen.
Could it be called something other than xmfr-h? also, where is the transformer located?
There were 2 different boards used on that furnace. It could just be called XFMR. You will most likely see a black lead on it. The transformer is down near the circuit board.Tim H41023.9347541667
I found the transformer, and the leads/terminals xmfr-h,n. I tested several times and kept getting 120 volts, instead of 24 or 0???
I apologize, I misspoke. You SHOULD have 120 volts across XFMR-H to XFMR-N. The 24 volts should be across C (common) to R on the board and I think you said previously you had no voltage there. So if the 3 amp fuse is OK, then with no voltage across C-R, the transformer would be burned out. Sorry, it's been a long day!
Is there a chance it could be the board? I took the transformer off, and took it to johnstone supply this morning.( I didn't see your answer until now) Anyhow, it didn't really make sense abou there being 120 volts, so I asked if they could test it for me, and it tested good. There is no action from either of the green led's on the board. They don't light up at all.
Yes, it's possible. Why wouldn't it make sense that there would be 120 volts at the board. A transformer has a primary (higher voltage) and a secondary side (lower voltage). Since you tested across XFMR-H and XFMR-N and got 120 volts, but nothing at C-R, it would make sense that the transformer could be bad. But if they're saying that it's good, you either have a bad connection somewhere, the 3 amp fuse is blown, or the board could be bad. Check across the Secondary side of the transformer with the transformer in place on the unit and see if you get 24 volts. If you do, and the fuse is good, replace the board.Tim H41024.6887499653
I'm sorry for the misunderstanding. What I meant was when you told me that I should have 24 volts at (what appeared to me to be) the incoming power to the transformer. Please don't misunderstand me, you are way more qualified than me and I really appreciate your advice. I just questioned that one thing, and I saw from your reply now why because it WAS supposed to be 120 volts.I am taking my daughter to school in an hour, after that I will go back to the attic and start working on it. I'll stay in touch and let you know what I figure out. Thank you again.
Yes, I apologize for that, that was my mistake. Across XFMR-H to XFMR-N you should have 120 volts as this is the primary side of the transformer. Typically you'd measure the secondary side across C terminal to R terminal. However, you could also go directly to your transformer secondary side and measure the same 24 volts. And I'd say if you do that and come up with 24 volts, and you're positive the fuse is not blown, then the board is most likely bad. Especially with no LED's lit up.
Alright!!! Took the circuit board off, there was a tiny burnt spot on the back. Took it off and went and picked up a new one from johnstone supply and I'm back in business!!! Thank you very much for your help.
Great!!! Glad we got through this one....