blows cold out of the vents sometimes when the heater is on?

2004 BUICK RANIER
175,000 MILES • 6 CYL
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VANESSA SMITH
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I just had a blower motor resistor with auto temperature control replaced.
Nov 28, 2022 at 12:32 PM
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STRAILER
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This can happen when the coolant level in the radiator is low. Here is a video to help you check the coolant and be sure the engine is cold before you check it.

https://youtu.be/GSE9skKnOgY

This guide can help as well:

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

Please go over these guides and report back.
Nov 28, 2022 at 5:45 PM
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VANESSA SMITH
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Heat does come out, then all of a sudden, the heat coming out of the vents turns cool while heat is still coming out of defrost. Then it will go back to hot air. There should not be any air coming out of vents because it's on defrost.
Nov 29, 2022 at 7:22 PM
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STRAILER
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If the coolant is full, then it sounds like you have a mode control actuator that is out. here is the location so you can check it out and replace it to fix the problem. Check out the images (below). Please let us know what happens.
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Dec 1, 2022 at 6:10 PM