Help troubleshoot HVAC?

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Old 06-30-20, 07:45 PM
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Help troubleshoot HVAC?

I was swapping out my thermostat for a nest and during setup the thermostat told me my Y1 has no power (in hindsight I think I just needed a common wire?). The internet said hvac equipment problems could be the problem and a good litmus test would be twisting my Y1, G and Rc together and see if my AC kicked on. There were some sparks but they eventually stopped. No equipment kicked on. I plugged the wiring back into the base and got a different error, no power on Rc.

So I started troubleshooting. None of my breakers were tripped. I went down to the crawl space to investigate and things smelled pretty bad and I could see some smoke coming from the air handler/furnace wiring area. Much more than what I typically associate with a blown fuse. After popping off the access panel I found this...



This picture was taken in the box behind the door switch.

Everything on the internet told me it was a fuse but I am pretty sure my board does't have one. This post reinforced that as I also have the 1012-925a IFC.


I guess I am just confused on what I should replace or where I should go from here. I am not even 100% that the picture I linked is the root of the problem. I think the door switch is the problem but I don't understand why that would burn up before anything else. I also don't understand why there is so much wiring in the box for a simple door switch.
 

Last edited by PJmax; 06-30-20 at 09:15 PM. Reason: added pic from link
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Old 06-30-20, 09:19 PM
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Welcome to the forums.

There were some sparks but they eventually stopped.
Good thing for protection.

Your picture is the junction box where the house wiring connects.
That device is the blower door safety switch that door hits when closed.

Some furnaces have fuses..... many don't.
The 1012-925a board is not fused protected.

You didn't post make or model so we don't know for sure what you have there but you need to locate the 24vAC transformer. (in blower compartment) There is a good chance it's melted.
 
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Old 07-01-20, 04:35 AM
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You didn't post make or model so we don't know for sure what you have there but you need to locate the 24vAC transformer. (in blower compartment) There is a good chance it's melted.
According to the manual sitting on top of the furnace (or maybe it's the air handler?) in my crawlspace, I have a rheem lx2000. Assuming it is the transformer, is this the component I should be looking for?

Thank you for the warm welcome and more so for the reply.
 
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Old 07-01-20, 04:48 AM
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Hi, thatís the transformer you are looking for, I would suggest connecting the 24 VAC supply from it through a fuse, some transformers have a built in circuit breaker installed.
what is that pic of?
Geo
 
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Old 07-01-20, 07:22 AM
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what is that pic of?
I think PJmax nailed it.
Your picture is the junction box where the house wiring connects.
I am going to go back down and see if I can find the transformer and pull it. Will grab some more pics.
 
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Old 07-01-20, 07:49 AM
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Alright. I have more pics..

https://imgur.com/a/lfB4UbB

I think the first pic is the transformer that I need to swap out. It does smell a little funny but the way it is encased prevents me from seeing any visual damage. I am thinking I just cut this piece out and take it to a local HVAC supplier for a replacement.

Second pic is just to show general layout of the compartment.

Third pic shows where I saw the majority of the smoke. It may have just traveled up from the compartment and into that area so it is possible it has nothing to do with this but just providing info. Don't want to pop that cover off unless you guys think it is necessary.
 
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Old 07-01-20, 08:29 AM
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I am thinking I just cut this piece out and take it to a local HVAC supplier for a replacement.
Will HVAC suppliers sell to general public? I am seeing mixed reviews online stating some vendors only sell to licensed contractors.
 
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Old 07-01-20, 09:54 AM
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Alright I've pulled it..

https://imgur.com/a/Y23CKMZ

Looks like there is some def melted bits on here. Sniffing the wire output hole it def matches the burn smell. Going to run this up to a supply store and hope I don't catch any flack.
 
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Old 07-01-20, 02:18 PM
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Update: first supplier I went to wouldn't sell to me due to "liabiltiy reasons" yeah okay. Got a replacement 24v transformer with a built in 3amp breaker switch on it and swapped it in. Turned the power back on, depressed the door safety switch and got lights on the IFC. Yay.

So now we are back to the original problem of the Nest thermostat showing no power to Y1. I am thinking running a common wire would resolve it. Can I just connect this unused blue wire to the contact in the photo?

https://imgur.com/a/7kk0YrR
 
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Old 07-01-20, 02:52 PM
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Hi, absolutely you can connect the spare blue conductor , if you have a multimeter test between the R &C on that control board to be sure that you have 24VAC.
If you jump R. Y1. G your cooling should start, just a test.
Geo
 
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Old 07-01-20, 03:28 PM
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Yeah I went ahead and stripped the blue and added it into the C terminal on both ends. Now the Nest thermostat is complaining about no power on Rh again. Makes zero sense to me.
When I am using my voltage meter, what am I using for the ground?
I am throwing in the towel for now and hooking my old thermostat back up. Getting sweaty and angry. Welcome any advice.
 
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Old 07-01-20, 03:31 PM
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I don’t suggest using the nest, this is one of the reasons. Lots of problems and issues to deal with, both during and after installation.
Plus some go outright crazy and cause damage to the equipment.
I wouldn’t use one if you gave it to me for free.
 
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Old 07-01-20, 04:14 PM
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I don’t suggest using the nest
Yeah I was expecting some of this sentiment but ultimately I would like to get it working.
 
  #14  
Old 07-01-20, 04:22 PM
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The voltage should be measured from 24V hot to common.
The common has to be terminated on both ends.
 
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Old 07-01-20, 04:38 PM
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You should measure....
24vAC from R to C
24vAC from R to Y
with the thermostat not connected. No nest base either.
 
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Old 07-01-20, 08:01 PM
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So I thought the nest head unit was bull****ting me but I finally took a multimeter down to the crawl space and took a reading of the red wire in the 1 terminal and sure enough, not hot, just like the thermostat was telling me. I looked on the ifc and the red wire wasn't even going to the R. It was wired into the float switch. Took a reading on all the terminals and the Rh and R were always hot, as expected. Not sure why 1 wasn't or even if it should be.

Anyways, rather that figure out why it wasn't hot or if it was supposed to be I ditched the 1,2, 3, 4 altogether and just matched the wiring on the switchboard to color. See photo. So now there are two wires going into all 5 terminals. Came upstairs and the nest thermostat started controlling everything no problem.

Thank you everyone for the help.
 
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Old 07-01-20, 08:41 PM
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That is some type of zoning board in your picture.
 
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Old 07-01-20, 10:20 PM
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That is some type of zoning board in your picture.
I think it's entire purpose is allowing control of the honeywell air ventilation system. It still serves that purpose and those leads didn't get moved.
As far as zones go I have a separate unit for my basement and a separate unit for my upstairs so not sure what other zones this could possibly serve.
 
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