Heat blows cold air no matter what

Tiny
SARAHG
  • MEMBER
  • 2004 CHRYSLER 300M
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 153,000 MILES
Beginning of winter I realized that my heat was blowing cold. I checked the coolant which was low, filled it and that fixed it briefly. Then it would only blow warmish when in motion. Come to a stop, cold as ice. Now, I never have heat, coolant appears full and yesterday the temperature gauge actually went up to 3/4 hot. What do I do?
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Saturday, March 16th, 2019 AT 6:58 AM

4 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,014 POSTS
Hi and thanks for using 2CarPros.

There are a few things that can cause this condition. However, based on your description, I honestly feel it is low on coolant. Recheck the coolant level, not only in the over flow reservoir, but also in the radiator.

Do this and let me know what you find. If it is low again, we need to identify where the leak is as well as what needs fixed.

Here are a couple links that show how to find a leak and repair it:

https://www.2carpros.com/articles/radiator-pressure-test

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

Truthfully, what you described doesn't sound like a plugged heater core or an issue with what is called a blend air door actuator. The actuator determines if you get heat in the vehicle, but it would not cause the engine to run hot. That is why I feel it is coolant related. If the coolant was allowed to get low enough, you could even have an air blockage.

Let me know what you find.

Joe
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Saturday, March 16th, 2019 AT 3:38 PM
Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

There are a couple of options here. Let's start with a flush and fill and see if that does the trick. What can happen it that over time you get scale deposits that break free and clog up your radiator, your heater core (which is basically a small radiator in your dashboard), and coolant hoses, etc. If you are not getting the desired results after that we have other directions to go to fix the issue. Either way a flush and fill is a good and necessary preventive maintenance for your cooling system.
I have included a link for you down below. Please go through this guide and get back to us with what you find out.

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Thanks,
Alex
2CarPros
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Saturday, March 16th, 2019 AT 3:42 PM
Tiny
SARAHG
  • MEMBER
  • 2 POSTS
Okay. Thanks. I agree that a flush and refill is needed. I've never had a car that didn't have an actual radiator cap! Anyways, I will let you know.

Thanks
Sarah
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Saturday, March 16th, 2019 AT 3:48 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,014 POSTS
Welcome back:

I don't know if you need it, but here is a link that shows how to flush and refill the system. Please make sure it isn't low. You don't want to be overheating the engine.

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Let me know if that helps.

Take care,
Joe
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Saturday, March 16th, 2019 AT 3:57 PM

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