Trane xl90 Combustion blower Issues

bjpaff

Hello all,

Here is the problem:

I have a Trane xl90 early 90's model BLU100k gas furnace. Last Friday, come home from work, house smells like frying electrical parts, trace frantically to basement, combustion blower motor fried, smoking and too hot to touch.

Do the full tear down, get a new one (after quite a bit 'o searching) and install it last night. Power up, demand heat, everything kosher for one cycle. Next cycle, runs through cycle, but i hear combustion blower still running. Run down stairs, it is trying to fry itself again. Shut everything down, smoke coming from *new* motor. Will not restart. I let it sit until this afternoon, and figure, what the hey, what can it hurt at this point. Motor fired right back up. Good news, motor *hopefully* not too screwed up from ordeal.

Question: Control Circuit board??? It has two outputs for the motor, "Hi" and "Lo". Could a relay be bad and be delivering twice the voltage it should be?

Already checked pressure switches, both are free and working to the best of my knowledge. I am planning on ordering another board tomorrow, just wondering if you have any last minute opinions before i drop another couple bills on this old gal.

Any thoughts are welcome.

B

redline

is this the motor for the blower or the vent?

bigMikeB

It isn't giving twice the voltage per se it's sending voltage to both windings at once, replace the board.

bjpaff

Thanks. Thats what I thought. Ill be sure to make another post tomorrow if it doesn't work out.

Thanks again

B