Heater fan stops working after truck warms up

Tiny
DONEMYCHORESSEEYA
  • MEMBER
  • 2012 FORD F-150
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 90,000 MILES
Even at minus 20 my truck starts wit out issue. Continuously
warms up with steady heat blowing from all vents. All functions work as it's
supposed to cycling through high to low fan and even A/C. But, once it reaches a higher temperature the heater fan shuts off completely. If I shut down for a few
minutes and restart the truck, heater fan works again for a bit.
Do you
have the same problem?
Yes
No
Tuesday, February 16th, 2021 AT 11:28 AM

1 Reply

Tiny
KASEKENNY1
  • EXPERT
More then likely this is a relay issue. What happens is the control module grounds the relay and it supplies power to the blower. If the relay is failing when it gets hot it basically disengages and the blower motor will shut off. When you shut the engine off and restart it, the relay is resetting. So we need to follow this guide on how to test the relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Once we know where we stand with the relay we can take the next step if needed. If we do then we need to track power through the blower motor circuit to find where we are loosing the power. It may be the control module not grounding the relay so we can test that when we get there.
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Wednesday, February 17th, 2021 AT 5:22 PM

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