Rheem Classic 90 Plus (model #: RGRA-10EZAJS) - Blower won't shut off

[jb8103]

If I'm 100% confident about anything, it's death and taxes.

Let me put it this way, we've seen no evidence of anything faulty outside the Black Box. My next move would be to replace it, but I could be wrong.

[jb8103]

with the 24v 2A Fuse near the Controller removed,

OR with either of the 24v power wires to the Controller removed,

Turn power ON...

Does the Fan still run ? (shorted Relay Contacts)

Also did you run this test? It will help prove the Black Box is bad, before you spend hundreds on a new one.

[RegUS_PatOff]

I just realized that the fan does turn off during the initial period when the thermostat calls for heat while the burner is turning on and getting warmed up and then the fan comes back on and stays on. Does this indicate something else to look at as the source of the fan staying on or is that happening somewhere else in the schematic?

looks like a bad Controller

[briandmiller]

Also did you run this test? It will help prove the Black Box is bad, before you spend hundreds on a new one.

In reviewing this post I realized that I had not done this correctly. I had only removed the wires from the thermostat, not the power wires. I just went back and pulled the fuse off the board and the fan does not come on in this state. Any clues on what that tells us?

[RegUS_PatOff]

looks like a bad Controller

[briandmiller]

I'l know soon. ordered one from Amazon. Should be here today.

[jb8103]

In reviewing this post I realized that I had not done this correctly. I had only removed the wires from the thermostat, not the power wires. I just went back and pulled the fuse off the board and the fan does not come on in this state. Any clues on what that tells us?

Actually I quoted the wrong post from Reg. I wanted the one asking for voltage across the relay. But anyway, if the limit switches proved to be closed, and with the blower turning off at start of sequence proving the relay is functional, with the thermostat wires out of the circuit, with the IFM, valve and burners working as advertised, there's nothing else left that I can think of.

[briandmiller]

New board got the furnace running fine. Thank you all for your help.

Now I just need to figure out what's going on with my Honeywell TrueSTEAM humidifier.

[applianceman18007260692]

Glad you could git her done

[jb8103]

New board got the furnace running fine. Thank you all for your help.

Now I just need to figure out what's going on with my Honeywell TrueSTEAM humidifier.

But...there can't possibly be anything wrong with a Honeywell TrueSTEAM humidifier!