[starfleet]

Hello, I have a 21 y.o. Armstrong Ultra 80 II gas furnace in very good condition that recently has started behaving in a very puzzling manner.

On start-up, the inducer motor will come on as usual, but as soon as the pilot gas valve clicks open and the spark igniter activates, the inducer motor will drop out for anywhere from 1 to 3 seconds, then come back on and the furnace will cycle completely normally.

With the help of a relative in the HVAC business, we did some diagnostics and proatively replaced some components which were original. I replaced the control board, pilot module, pilot assembly and gas valve. Yet the problem persists.


Pretty much the only components not replaced are the 24v transformer and the inducer motor itself. The inducer seems to be working fine, in that if we disconnect the 24v wire to the pilot module and start the furnace, the inducer runs without dropping out.

Any thoughts?

Thanks