Once it reaches a higher temperature the heater fan shuts off completely

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.

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

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.

Image (Click to make bigger)

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

+1

Wednesday, February 17th, 2021 AT 5:22 PM

DONEMYCHORESSEEYA

MEMBER
3 POSTS

A previous reply suggested the Blower Motor Resistor so I changed that but it did not fix the issue. With my limited experience I went to the next available part, Blower Motor. A few curses and a couple of scraped knuckles later the issue was fixed. Blowing continuously without fail. Thanks for the follow up.

Was this

answer

helpful?

Yes

No

Thursday, March 4th, 2021 AT 6:37 AM

KASEKENNY

MECHANIC
18,907 POSTS

I have been there many times. They are only worth it if it fixes the issue.

Thanks for the update and using 2CarPros. Please come back in the future.

Was this

answer

helpful?

Yes

No

+1

Thursday, March 4th, 2021 AT 6:25 PM