[HckMass]

I have a Goodman GMH8 furnace that is three years old. The draft inducer motor goes on for about 2 seconds then shuts off and then keeps cycling until I shut the furnace off. It has been doing this for three days. My plumber came over and looked at it and after checking some wires it came back on. It has done it each time first thing in the morning when the programmable thermostat is calling for the preset morning cycle to start. Any advice would be greatly appreciated. Thank You.

[Dennis1523]

There is a vacuum switch that goes to the inducer motor. Pull the tube off the vent and suck it while starting the unit. If it works as long as you can suck you know the switch works. Also hold a match or lighter up to the flu pipe opening and see if it sucks the flame up into the flu. If not then you have a obstruction of some kind and it is not venting properly. Also check that tubing for cracks.

[HckMass]

Thank you for the help. I took the tube off the vent and tried what you said. I noticed that every time the switch engages the inducer fan turns off. But every now and then the furnace will fire and run when the tube is in place. Do you think the pressure switch is bad?

[Dennis1523]

Check out this video. It may help you or even search for other videos that may answer your questions.
http://www.youtube.com/watch?v=9WI-uRRx0o0&feature=related

[Dennis1523]

Check for operating voltage at the inducer motor and see if it is getting voltage even when it shuts off. It could be the motor.

[jac1599]

I am having this same problem. The inducer will run for about 1-2 seconds, and then stop. Then run about 1-2 seconds, and stop. Unhook the vacuum line to the pressure switch and the inducer will start and run like it should. However, we get no heat because the board thinks the pressure switch is open. Applying suction to the vacuum line, you hear the switch close, and the inducer immediately stops running and goes back into its 1-2 second cycle phase.

[Mchecchio]

Jac1599 I have the same problem. Were you able to figure it out"

I am having this exact same problem. The inducer will run for about 1-2 seconds, and then stop. Then run about 1-2 seconds, and stop. Unhook the vacuum line to the pressure switch and the inducer will start and run like it should. However, we get no heat because the board thinks the pressure switch is open. Applying suction to the vacuum line, you hear the switch close, and the inducer immediately stops running and goes back into its 1-2 second cycle phase.

[MacGyver333]

The vacuum switch needs to be open before the draft motor starts then close and stay closed once the motor starts otherwise it will continue to cycle. This is to make sure there is enough vacuum to keep the gas inside the burner section. Pull the vacuum tube and use a pipe cleaner and make sure the connection points are clear. A white powder can build up on the burner section side, also make sure the tube is not damaged any cracking or if the connection is not tight the sensor will not work. Hopes this helps