Payne PG92S - fan works but no flame

timothymiles

I turned off my 8 year old Payne SG92S (propane) at the thermostat a couple of weeks ago and turned it back on now as it's getting cold again. Now, if I put the fan on "on" it runs contiuously yet if I put it on auto, it doesn't start.
Even with the thermostat turned to heat and at a temperature where the "on" indicator is visible, there is no flame or attempt to lite the flame. also, if I put it the fan on "on" it runs but doesn't stop like it used to to allow the flame to be ignited and preheat.
I can't find where on the furnace control board I need bridge (R, G, B/W) in order to test to see if I can trigger the flame to ignite when the thermostat triggers "heat on".
I don't know where to look to determine if it's the thermostat (much older than the furnace) or something internal in the furnace.

thanks for any input.

Jamie Hall

What wires do you have at the thermostat? If the thermostat wires are labelled — or the terminal — find R and W and jump between them.

SuperTech

If the thermostat is working then the first thing that should happen is the draft inducer should come on. If the inducer is energized and not coming on the furnace control board will show a fault code because the pressure switch that proves the inducer is running never closed. You could have a inducer motor or I've seen furnaces where a mouse or bird gets into the inducer and prevents it from running.

Ironman

Turn the power off and then back on to the furnace. If it attempts to run but fails, then the issue is in the furnace.

pedmec

look thru the inspection window and count the flashes. if you hhave anving a error you would get flashes from the control board. no flashes mean no errors. all your codes are normally on the inside cover. if not then in the manual

OldManwithStick

Can you provide the full model number off this unit please?

EdTheHeaterMan

Depending on the year built, there may be a small round window in the blower cabinet door to view the furnace control board. Look thru that hole and count the blink code before you open the door. That is because there is a door switch on that door. That switch will cut the power to the control board and you may lose the last code stored in the control. Once you know the blink code, you can open the door and look at the sticker on the inside of the blower door and that may give you a place to start with diagnosing the problem. Look on page 13 of this manual https://www.shareddocs.com/hvac/docs/1009/Public/08/OG-9GFP-08.pdf for the information you seek.

timothymiles

This particular model doesn't have an inspection window nor does it have a display for error codes but here is a weird twist. After not working for a couple of days and before I had a chance to bridge the R and W wires, the darned thing started working all by itself. How in the world does that happen? I'm thrilled but also concerned. It's not much of a problem given the weather now and in the days to come but something tells me 5 months from now if it quits again, I'm going to be in big trouble.

pedmec

page 13 of the manual, last paragraph. it clearly states that you have both inspection window and led status lights. I have not seen a furnace with an integrated furnace control not have led status lights for troubleshooting. Even the low end models have them. And Payne is a part ofof the CarrierCarrier and Bryant family.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1801592#Comment_1801592

i only guessed at the I/O manual, so @timothymiles may have an older control that does not have diagnostic LED lights. This will make it harder to determine the reason for the fault. If @timothymiles can post a photo of the model number and a picture of the control board that is usually located in the blower compartment (but not always), I could get a better answer.

One thing that does happen to these wiring harnesses and control boards is that there is corrosion that builds up on the wire connections where wires get connected by screws, Molex® plugs and card edge wiring harnesses.  The simple act of unplugging and replugging in the connector will often clean the corrosion off the friction fit connector making a better circuit connection.   That is often the reason that things get miraculously fixed without knowing that you even did anything.

SuperTech

Maybe it was just weak thermostat batteries that aren't strong enough to close the R-W contacts? Couldn't hurt to try replacement batteries.