Transducer Trouble

[Coltsfan59]

I have an International Comfort Products furnace distributed by Heil. Model #: c9mpd050f12c2.  Serial #: a081568679. The transducer will not turn on consistently. It clicks like it wants to go and moves slightly. The codes blinks 3 times. I've replaced the transducer, pressure switch, and the door switch. With resetting, it will eventually run. Sometimes it runs for about 5 seconds then stops. Please help.

[Admin]

Try to measure 120V across the inducer motor terminals.  It should be constant after a call for heat. 

You may need to replace the control board if that relay is failing.

I would also disconnect W at the furnace, the wire coming from the thermostat.  Jumper R and W, at the furnace, to call for heat and rule out a thermostat problem.

You can wire your inducer motor to constant power and cycle the furnace.  Leave the pressure switch tubing disconnected from the pressure switch and reattach it after you hear the click, otherwise the constantly running inducer motor will cause a pressure switch error for being stuck closed.

If the furnace fires up and runs without stopping it likely means the control board will need to be replaced.