Heater blowing out cold air after replacing the thermostat?

ERICKA2088

MEMBER
2012 JEEP GRAND CHEROKEE
3.6L
4 CYL
4WD
AUTOMATIC
136,000 MILES

My car overheats a lot, and I changed the thermostat 2 days ago. The heat was extremely hot. I went to drive my car the next day and gauge went all the way to H, car blew out nothing but cold air!

Thursday, December 15th, 2022 AT 4:35 PM

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

Have you rechecked to make sure the coolant is full in the radiator? When you replaced the thermostat, did you replace the entire thermostat housing/thermostat as a unit?

Do this. If the coolant is full, start the engine, turn on the heater, allow the engine to reach operating temperature, and turn off the engine.

Feel both heater core hoses at the firewall. Both should be hot. Let me know if that is the case.

Let me know what you find.

Take care,

Joe

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Thursday, December 15th, 2022 AT 9:02 PM

ERICKA2088

MEMBER
2 POSTS

Thank you for responding! The entire housing was replaced. So, I went to warm up my car this morning and all the coolant was on the ground. I poured more coolant and drove my car and the heat has been extremely hot since then.

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Friday, December 16th, 2022 AT 5:22 PM

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

Okay, if the coolant leaked out, that is why you didn't have heat. So, we need to locate the leak and repair it.

Have you done a general inspection to see if there are any indications of where the coolant may be missing?

Also, take a look through this link and let me know if you are able to locate a leak:

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

Let me know.

Joe

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Friday, December 16th, 2022 AT 9:41 PM