Furnace Control Board dead? HVAC just came out to diagnose.....

Hey guys,

HVAC just came out to try to diagnose my furnace which is not turning on. When he got there he jumpstarted inside the furnace and it turned on, blowing hot and and everything. He says the control board is fried.

He then went to my nest and then jumpstarted there. It worked. I saw the look on his face and he looked confused.....which worries me....he says the Nest might be bad, which he says he's never seen. At the end I paid $550 for a new control board, transformer and labor.

Parts will be shipped in and I have another appointment to install everything. Is there anything I can do right now? They looked really confused that they were able to jumpstart at the thermostat level.....I have a old thermostat that I can try to hook up....

Thanks guys, I have no idea about HVAC.

 

Welcome to the forum!! Based on your description you are probably correct in being suspicious. If the control board is fried then you should not be able to jump it at the thermostat and have it work properly. If I was you, I would do my own basic troubleshooting. At the control board you can use a small jumper wire or even a paper clip to jump between R and W to start the ignition sequence and see if it operates properly. Then you can jump the R and W wires at the thermostat to see if the furnace will fire up. It sounds more like a thermostat issue to me.

Are you saying he has not installed the transformer yet? Do you show any error codes on the thermostat? Here is a link to the pro version Nest thermostat guide: http://support-assets.nest.com/image...ller-Guide.pdf

I would connect the old thermostat and see if it will work to operate your system.

 

I can't seem to find the old thermostat, but what does it mean when you can jumpstart a system at both the furnace level and the thermostat level?

Does that mean that the controller board can still works? My AC still works perfect, the fan still works perfect when controlled with the Nest.

The furnace is a GF Ruud Ugpn05eauer. The total cost for the control board was $314, transformer is $57 and the labor is $100.

What else do you guys think it might be? I don't think my Nest is bad - what exactly does a jump do that a bad controller board can't do?

 

If you don't try the jumper wire like the Dawg mentioned then you will have no idea if it's a control board or thermostat issue.

 

No no, the original HVAC guy jumped it and it worked. At both ends, the furnace and thermostat. That's why he looked so shady when he left.

So I just found my old thermostat and guess what .........the heater works. My Nest must be malfunctioning.....

I just gave the HVAC guy a call and he was very shady on canceling the part order. This was a wrong diagnostic so I'm going to fight this one, maybe even do a credit card charge back.....

Long story short - everything is working now.

 

I am completely lost here.... you paid the guy ahead of time for the parts ??
That's a red flag right there.

I would never consider charging the customer ahead of time for the parts for the repair.

 

Yes, I thought it was standard practice so, since it was not available anywhere and had to be ordered through a special retailer so I agreed.

Now I'm going to get anxiety about fighting them to get my refund.