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Heating has started blowing cold air?

Tiny
KILAMAJARO77
  • MEMBER
  • 2002 BUICK LESABRE
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 84,620 MILES
Had a coolant flush yesterday at a local shop. Had good heat through all the vents when I left the shop. Drove 5 miles and it started blowing cold air. Drove back to the shop / my top Rad hose had collapsed so he added some coolant and sent me on my way with medium heat and now my defrost and vents blow cold air, but my floor vent blows warm air. Now I ran the car today and then released any air from the valve on top of the thermostat housing till just anti-freeze came out. New thermostat 2 weeks ago. What could be going on?
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Wednesday, December 4th, 2024 AT 9:21 PM

14 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
It sounds like you have an air bubble stuck in the heater core which is common. I would get the front of the car in the air (jack) and remove the radiator cap, (engine cold) then start the engine and allow it to get hot while having the heater on full fan speed and heat. This should help the air escape; you can do the same thing while raising the of the car as well. Here is a video that can help as well and a guide:

https://www.youtube.com/watch?v=SNRb6pSwYuU&t

This guide can help you raise the car:

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

Please upload pictures or videos in your response of any problems so we can see what to help you with.
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Thursday, December 5th, 2024 AT 1:50 PM
Tiny
KILAMAJARO77
  • MEMBER
  • 17 POSTS
I'll try that in the morning. I'm just going to run it up on ramps.
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Thursday, December 5th, 2024 AT 6:21 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Sounds good, let me know how it goes, the heater worked before the work was done correct?
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Friday, December 6th, 2024 AT 9:44 AM
Tiny
KILAMAJARO77
  • MEMBER
  • 17 POSTS
Hi Ken,
Okay, that worked. I have good heat coming out of the floor vent and medium coming from the defrost and vents. It's much better than it was. I don't know why there would be a difference in the temperature between the two. Thanks for your help Ken.
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Saturday, December 7th, 2024 AT 11:41 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Saturday, December 7th, 2024 AT 12:46 PM
Tiny
KILAMAJARO77
  • MEMBER
  • 17 POSTS
So having 2 different temperatures like that is normal?
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Saturday, December 7th, 2024 AT 12:53 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Can you explain a little more what is going on?
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Sunday, December 8th, 2024 AT 9:54 AM
Tiny
KILAMAJARO77
  • MEMBER
  • 17 POSTS
Hi Ken, sorry for the delay. I have cancer and I have good days and bad days. Friday night I went for about a 30-mile drive. I had good heat coming from the floor and medium from the vents and defrost. By the time I got home I was getting cooler air coming from the defrost and vents and medium from the floor vent. All the time my temperature gauge stayed at the halfway mark (normal). Checked coolant level the next morning and it was full. Maybe I should change my thermostat back to 185 degrees instead of 192. Suggestions?
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Tuesday, December 10th, 2024 AT 11:57 AM
Tiny
KILAMAJARO77
  • MEMBER
  • 17 POSTS
Bad water pump?
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Tuesday, December 10th, 2024 AT 12:57 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
I am sorry to hear about your troubles, :/

If the engine is not overheating the water pump is okay, to me it sounds like the heater core needs to be flushed. I would remove the heater hoses and use a garden hose to help flush the core. Check out the images (below). Please let us know what happens.
Image (Click to make bigger)
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Wednesday, December 11th, 2024 AT 10:03 AM
Tiny
KILAMAJARO77
  • MEMBER
  • 17 POSTS
Hi Ken, thank you. Okay, I'll give that a try and get back to you. Maybe Friday.
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Wednesday, December 11th, 2024 AT 4:33 PM
Tiny
KEN L
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Sounds good, have a nice weekend!
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Thursday, December 12th, 2024 AT 12:29 PM
Tiny
KILAMAJARO77
  • MEMBER
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You too. I was thinking it could be the heater core itself but theres no fogging inside the car. No leaks inside on the floor. No coolant lost anywhere so. I'll find out ! Later
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Thursday, December 12th, 2024 AT 7:41 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Yep, it can be just clogged internally which is common.
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Friday, December 13th, 2024 AT 12:42 PM

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