If I turn the power off and restart the unit, the fan comes on but I don't see or hear the igniter and I'm not able to tell if the gas is coming on either, I assume that is a safety feature

Hi Riles and welcome, the fan you hear running is the inducer fan, it should start and activate a pressure switch. Do you have good airflow outside at the exhaust? Make sure the pipe is clear. If that checks out I would suspect the pressure switch is bad. Good luck

What fan? Air handler or inducer? Are there any codes shown on the board?

this is a pretty old unit, there are no trouble codes or display

Quote:

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Originally Posted by parttime

Hi Riles and welcome, the fan you hear running is the inducer fan, it should start and activate a pressure switch. Do you have good airflow outside at the exhaust? Make sure the pipe is clear. If that checks out I would suspect the pressure switch is bad. Good luck

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thank you, is there a procedure for checking the pressure switch with a multi-meter, or what values should I be looking for? voltage or resistance?

Hi again Riles, yes there is a procedure for checking the pressure switch, but it involves special tools that are rather expensive. If it was mine and I was sure the inducer fan was blowing strong and the exhaust was clear I would turn off the furnace power, disconnecting the two wires going to the pressure switch and temporarily connect them together, set the thermostat for heat, then put the power in and see if it fires up. If it does then I would kill power and replace the switch. This is something I would do to trouble shoot the furnace and I would never​ run it like this. Good luck

I just finished with the pressure switch continuity test and it appears that the circuit remains open weather the induction fan is on or off, so now to locate one on a Saturday, thank you parttime

I just cut the power and connected the 2 pressure switch wires and when I restored power and set the thermostat for heat and nothing happened, same as before, induction fan only, not sure what to make of it now

Rile, did you block the door switch when you did the test?

According to the Rheem website, this series has spark ignition and a "Diagnostic control board". Are you sure there is no LED on the control board. Did you look for a fuse on the board. There are roll out switches and an upper limit safety. Download the manual from Rheem and look at the schematic.

Rheem Furnace User Manuals Download - ManualsLib

yes sir, door switch accounted for

Riles can you post a picture, does one of the panels have a schematic?

my particular model is not listed on the rheem site or manualslib, it's been kicking my tail without anything to refer to, you guys are awesome but a picture is worth a thousand words and electrical is not my strong suit

Attachment 48046Attachment 48047Attachment 48048

I hope this works

I found an LED on the hot surface ignition module but overlooked it because it doesn't come on during regular operation, when there is a command for heat, I can hear the module click once and the inducer fan runs but the LED never lights up, there is 24v to the module

Hi again Riles, the pictures didn't do much for me and my old eyesight, sorry. Maybe someone else can make more of it.

Yep, sure looks old but, I knew there was a board somewhere with an inducer and a pressure switch. Looking at your pictures: That is a normally open pressure switch and will close on negative pressure from the inducer. The little rectangular black plate with 2 wires is the high limit. Make sure there is 24 VAC across it when calling for heat. Looks like a roll out safety to the left of the gas valve. They are resettable if tripped, small toggle switch. Check for a fuse on the control board, 5 amp car type.

there is 26v across the high limit switch when calling for heat, is too much a problem? and as far as the roll out safety(pictured) I can't locate a toggle but the top has a loose kind of red button deal on itAttachment 48049

Riles you can test the rollout switch using your meter, test for continuity.

it tested o.k.