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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I am having trouble with my gas furnace. The blower and

Customer Question

I am having trouble with my gas furnace. The blower and burners stop working once a day over the past 3 days. If I completely shut it down for a long period of time (over night) it works again
Submitted: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.

This can be caused by a variety of things. If the whole furnace shuts down, it could just be a defective thermostat since the thermostat tells furnace to come on. Do me a favor, next time this happens, before you touch anything, go down to furnace and look in the small window, see if you get an LED flash code, and if so, how many flashes. Also, full model number would be helpful.

Customer: replied 1 year ago.
Single flashes, model no.AUC080C942A0
Expert:  Tim H. replied 1 year ago.

No, single flashes doesn't help me. I need to know how many flashes before a pause.

Expert:  Tim H. replied 1 year ago.

Perhaps I misunderstood you. Are you saying there is a single flash, then a pause, then a single flash, etc?

Expert:  Tim H. replied 1 year ago.

There is no single flash code according to the manual. Here are the possible flash codes:

Customer: replied 1 year ago.
It's flashing. I meant it is just a single flash at a time
Expert:  Tim H. replied 1 year ago.

There is no single flash code. It will be two flashes and a pause, 3 flashes and a pause, 4 flashes and a pause, etc. Did you open that file I sent you?

Expert:  Tim H. replied 1 year ago.

Realize, if it's just flashing slow and steady, this is just a call for heat and indicates no error. The flash code I want to see is when the furnace actually shuts down like you said and won't restart. This will indicate an error code. You may have to watch it for a while before this happens.

Customer: replied 1 year ago.
It flashes fast when it is running. Slow when it stops. There is never a pause even when shuts down.
Expert:  Tim H. replied 1 year ago.

Again, I sent you a copy of the flash codes. Flashing slow, no call for heat. Flashing fast-call for heat. I don't care about these flashes, this is part of normal operation. What I care about is when unit shuts down when it should be on, that you go down and check it BEFORE YOU TOUCH ANYTHING and tell me what the flash code is, if any. Otherwise, as I said before, could just be a bad thermostat.

Customer: replied 1 year ago.
Ya I've seen your copy of the flash codes, it is also on my furnace. I don't know how many ways I can say it's only single flashes. There is no error code. Did I spend $28 for you to send me a copy of a sticker that is already on my furnace. This is one of the first things I checked when my furnace started acting up.
Expert:  Tim H. replied 1 year ago.

Chris, when a furnace has an error code, it will happen when the furnace shuts down when the thermostat is still calling for heat. It will not happen during normal operation. If your furnace actually has an issue, then the furnace will shut down on a call for heat. We don't even know at this point if there is a problem with your furnace. It could be a bad thermostat. That's why the next time that the furnace stops (when it should be on), I want you to go check for a FAULT flash code before you do anything.

Customer: replied 1 year ago.
The furnace is shut down. It has been shut down every time I have answered this question. This is why I'm frustrated. I keep telling you that there is no error code when the furnace should be working, it's just slow single flashes.
Expert:  Tim H. replied 1 year ago.

Do you have access to a voltmeter?