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RJackson4016 · Sep 13, 2014, 02:10 PM

I am working on an American Standard furnace that will not cycle off & on. It works only in the "On" position but the air conditioner cycles on & off fine. I have already replaced the thermostat.

Can someone tell me what the problem may be?

bitters · Sep 13, 2014, 02:50 PM

What's model number of the furnace?

RJackson4016 · Sep 20, 2014, 03:59 PM

My model # is TWGO25A140B1

bitters · Sep 21, 2014, 11:23 AM

Take the stat off and move G wire to Y terminal, so you have two wires on Y and see what happens. Turn power off to furnace.

I can't find anything on that model #.

RJackson4016 · Sep 21, 2014, 02:07 PM

Thanks for the response. I turned off power to furnace and moved G wire to Y terminal, turned power back on to furnace and tried to cycle it on. Nothing.

bitters · Sep 21, 2014, 03:57 PM

Did the AC come on? But no fan?

RJackson4016 · Sep 21, 2014, 06:29 PM

Did not hear the AC kick on-definitely no fan. The AC cycles on and off normally. But the heat works only when on ON and not when on AUTO.

bitters · Sep 22, 2014, 06:16 AM

Can you double check the model #? What brand is the furnace? The model number should be inside the top panel (burner compartment) of the furnace.

RJackson4016 · Sep 22, 2014, 06:43 PM

American Standard TWG025A140B1 I don't know if the 0's are O's or vise-versa.

bitters · Sep 23, 2014, 09:12 AM

There is very limited info about your furnace on the net. Does the furnace have electric heat coils? If so it could have a bad sequencer. Can you post a close up pic of the wiring diagram?

RJackson4016 · Sep 24, 2014, 04:36 PM

Appreciate your help bitters! The furnace have electric heat coils. I hope you can read these diagrams. Attachment 46608 Attachment 46609

bitters · Sep 25, 2014, 09:17 AM

Originally Posted by RJackson4016

Appreciate your help bitters! The furnace have electric heat coils. I hope you can read these diagrams. Attachment 46608 Attachment 46609

I can't open your attachments. Still would like to see them.

parttime · Sep 25, 2014, 09:21 AM

Rjackson, this link will show you how to post a picture, I hope it helps. https://www.askmehelpdesk.com/suppor...es-783127.html

RJackson4016 · Sep 25, 2014, 05:47 PM

Thanks parttime! Try this bitters. (Attached below)

bitters · Sep 26, 2014, 09:08 AM

Thanks for the drawings. I don't see see anything in there that would be causing the problem. If you have a voltmeter, set the stat to cool and fan to auto. Then go to the furnace and put your meter on B and T on the circuit board. Make sure the door switch is engaged. If you have 0 volts something is going on in the stat. If you have 24 volts then the circuit board has a problem.

RJackson4016 · Sep 26, 2014, 05:36 PM

Okay. I have a meter and will do that, but I have replaced the stat so it's fairly new.

RJackson4016 · Oct 7, 2014, 05:45 PM

Hi bitters. I realized the wire diagrams I sent to you earlier were the wrong ones. This diagram is from the "Heater Control Box" and maybe it might help you with my problem. Thanks again.

Grady White · Oct 7, 2014, 06:19 PM

The diagram is no where near complete. We need to be able to see the whole thing.

hkstroud · Oct 7, 2014, 06:45 PM

Are you still working on the furnace problem where you said the heat would not come on when the switch on the thermostat was set to "ON"

RJackson4016 · Oct 9, 2014, 05:40 PM

Yes-I'm thinking about searching for the relay or sequencer online as a process of elimination, hoping that will solve the problem.