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?

What's model number of the furnace?

My model # is TWGO25A140B1

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 #.

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.

Did the AC come on? But no fan?

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.

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.

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

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?

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

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

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

Rjackson, this link will show you how to post a picture, I hope it helps. https://www.askmehelpdesk.com/support/we-new-sticky-posting-pictures-783127.html

Thanks parttime! Try this bitters. (Attached below)

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.

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

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.

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

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"

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

Really can't tell anything from the diagram, too big.