RHEEM RGDG-05EAUER gas furnace

[washu42]

I had someone check this a couple weeks ago, was told the flame roll-out switch had been tripped.  He re-set it and everything worked fine.  Today woke up to same problem, but when I re-set the switch it still doesn't work.  The small fan motor (I believe it's the IDM) starts up, but the ignitor never glows and the motor shuts down after a while. 

anyone available to help w/this?

[dkpd1581]

Typically there is a single shot fusible link.  It is an over temperature safety device that once tripped cannot be reset....it must be replaced.

If you have a roll out instance, you have a very serious situation that requires more than a reset.  You may want to have your unit more thoroughly and professionally checked out.

[applianceman18007260692]

I was just thinking that the guy came in found the rollout and reset it. probably in the vent pipe. Did he stay a while and clean the burners or vent, or was he there for 5 minutes? I would get his ass back out there and make him oil the motors and clean the damn heater right. My opinion.

[washu42]

Thank you for your advice about previous repairmen.  His ass isn't available this week, and I need my heater working:?

Is there anyone who can help walk me through what part I need to replace? I have a multimeter and the troubleshooting guide, just not sure what some of the terms mean or how to check the part.  I have vaccumed the furnace, I don't see any burned connections or cracks in the manifold. 

[MrFixit246]

Please do not ASS-U-ME the roll out switch tripped erroneously. There is a reason they are there. One of the possibilities is the heat exchanger could be cracked. When this happens the flame will roll back a little and cause the roll out switch to overheat. I think this is what the other person was referring to when he said serious situation is possible.

In the great white north I have seen many cracked heat exchangers and even saw a family pulled out of a house on stretchers because of it. DO NOT by pass them or ignore them.

If you are certain that is not the problem a couple more things to check are the ignitor, check resistance. The induced draft motor will run a while then shut off and lock out if the burners do not ignite. Do you hear the gas valve click and gas go to burners for about 8 seconds? If so you are looking at an ignitor.

BTW you normally won't see the cracks in the Heat Exchanger unless you pull the heat exchanger out or use a boroscope and run it up into the heat exchanger.

MrFixit

[applianceman18007260692]

Look for a fuse like pete(dkpd1581) said, if it is open you won't have ignition:

[washu42]

Thank you for your response - I do appreciate the fatal potential of failure in this system.  After I vacuumed everything out and checked to make sure all wiring connections were tight, the system worked.  I'll keep an eye on it & try to line up a good referral to have it checked if it goes out again.

[applianceman18007260692]

Glad you could get it going. If you replaced no parts it was probably a loose burner groundwire.