Heater stopped blowing hot air on a idle

Tiny
HIRO.KOBAYASHI76
  • MEMBER
  • 2013 FORD F-150
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 113,000 MILES
I have the truck listed above with a 3.5L Ecoboost, 130,000 miles. I recently noticed that my radiator fan is constantly kicking on and off more frequently. All temperatures seem normal. Every now and again the vent cold air would not blow cold air on an idle but once I start driving and turn the A/C on it would get cold. Recently while driving the heater stopped blowing hot air on a idle. Radiator fan still kicking on and off more frequently. I did notice the coolant level was low, refilled it properly and did not notice any leaks. The heating and cooling problem stopped for a bit, but the fans still kicks on and off frequently. Today the heating problem returned but also at highway speed, not just at an idle.
Thursday, December 31st, 2020 AT 5:14 AM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

This could be a couple of things. Have you rechecked the coolant level? Is it full?

If it is, try this. Start the engine, turn the heater on high, and allow the engine to reach operating temperature. When it does, feel both heater core hoses. Both should be hot. If they are, then the problem is likely related to a faulty blend air door actuator in the vehicle. If only one is hot and the coolant is full, either we have air blocking the flow or the heater core is plugged.

Try that and let me know what you find. Also, here is a link you may find helpful:

https://www.2carpros.com/articles/car-heater-not-working

I will watch for your reply.

Happy New Year,
Joe
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Thursday, April 15th, 2021 AT 1:42 PM
Tiny
HIRO.KOBAYASHI76
  • MEMBER
  • 4 POSTS
What about the radiator fan constantly turning on and off?
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Thursday, April 15th, 2021 AT 1:42 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
If the coolant is low, that could explain the fan. Have you checked the coolant level?

Joe
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Thursday, April 15th, 2021 AT 1:42 PM
Tiny
HIRO.KOBAYASHI76
  • MEMBER
  • 4 POSTS
Guess it was a gallon and a half low of coolant. Everything seems to be working now.
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Thursday, April 15th, 2021 AT 1:42 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Glad to hear you got it working. However, that is a lot of coolant. Let me know if you run into other issues with the cooling system.

Feel free to come back anytime in the future. You are always welcome here.

Take care,

Joe
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Thursday, April 15th, 2021 AT 1:42 PM
Tiny
HIRO.KOBAYASHI76
  • MEMBER
  • 4 POSTS
I live in Houston, and prior to that Hawaii so two pretty humid places and run the A/C all year. Never had to add coolant since I bought the truck at 50,000. Could it be that it just evaporated slowly in time?
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Thursday, April 15th, 2021 AT 1:42 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

That amount would be odd. I suspect there is a leak. There are other things that can cause if such as a bad head gasket. Take a look through this link. It explains common symptoms of a bad head gasket. I'm not saying this is the issue, but it will at least give you some things to keep an eye out for.

https://www.2carpros.com/articles/head-gasket-blown-test

Also, here are a couple of links that explain how to check for and repair a leak. Take a look through it as well.

https://www.2carpros.com/articles/coolant-leak-symptoms

https://www.2carpros.com/articles/car-is-leaking-coolant

I hope this helps. Let me know if you have questions or need help with anything.

Take care,
Joe
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Thursday, April 15th, 2021 AT 1:42 PM

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