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Had similar condition with a Goodman gas furnace. Search for the thread called "blower on furnace is possessed".

Hope it helps you fix your problem.

I replaced the control board yesterday and the unit is working correctly again.

Thank you bkspero! Your advice was perfect. I picked up a new board on eBay and swapped it for the old one just as...

Do the voltage measuremnts above mean anything to anyone?

NorthernHeat,

I measured low voltage at thermostat. I left the system in the OFF/AUTO mode and the blower is still automatically cycling on and off.

When the blower is OFF:
Common+red=27V...

Thank you for offering me your great advice everyone.

NorthernHeat, I will make the voltage measurements to verify that the board is bad.

Thank you bkspero. The shut-off delay makes sense -...

My model number is GMP 075-4.

By the way, I don't see an adjustable limit switch.

Sorry about that, correct model number for gas furnace is GMP 075-4

(Fortunately) the problem occurs somewhat consistently. Blower motor is OFF for approx 5-10 minutes, then the blower turns ON by...

Thanks for your suggestions hvac1000.

I'd like to try and make the repairs myself. My furnace is a Goodman model 1026. It is about 10 years old.

I think I've been able to rule out any problems...

The blower on my Goodman gas furnace came on all by itself tonight? Every 5-10 minutes the blower turns on for approx 1 minute then turns off by itself. Then the cycle repeats.

I verified that the...

Had a similar problem...

House was very cold; could not maintain temperature.

Gas furnace would reach set point, shut off, and then not turn on again.

Only way to fire heater (Goodman) was...

Short and to the point