Nordyne fan turns off & on constantly

[brokenspoke]

Hello, I have a Nordyne MGBB-070ABFC-06 and just last night I woke up to hear the fan kicking on & off constantly. When the burner comes on & gets hot the fan kicks on for about 5 seconds then turns off then after about 10 seconds it does it again. The burner is staying lit the whole time & I can switch the fan from auto to on at the thermostat & it heats just fine. After turning the furnace off at the thermostat the fan continued to do this for about 10 minutes then finally quit. I looked in the furnace & from what I can tell by the wiring diagram there is a limit switch & a fan switch for the blower. Neither one are adjustable. Is there a way I can test these? What else might it be? And of course last night was the coldest night we've had this year & my furnace acts up. Go figure.

[Robert]

Locate each one, 3 limits and one fan switch total.


When it starts acting up, all four should read 0vac across the two terminals whenever you have a call for heat and burner is lit.


At time it shuts off, test and see if any show 120vac, if so, they are bad.


They should remain closed.


Closed = 0vac

Open = 120vac




Most common is the Fan Switch.


We have any parts needed, let me know if you'd like ordering and pricing info.



Thanks,
Robert