Heating has started blowing cold air?

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?

Wednesday, December 4th, 2024 AT 9:21 PM

18 Replies

KEN L

MASTER CERTIFIED MECHANIC
50,192 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.

Was this

answer

helpful?

Yes

Thursday, December 5th, 2024 AT 1:50 PM

KILAMAJARO77

MEMBER
19 POSTS

I'll try that in the morning. I'm just going to run it up on ramps.

Was this

answer

helpful?

Yes

Thursday, December 5th, 2024 AT 6:21 PM

KEN L

MASTER CERTIFIED MECHANIC
50,192 POSTS

Sounds good, let me know how it goes, the heater worked before the work was done correct?

Was this

answer

helpful?

Yes

Friday, December 6th, 2024 AT 9:44 AM

KILAMAJARO77

MEMBER
19 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.

Was this

answer

helpful?

Yes

Saturday, December 7th, 2024 AT 11:41 AM

KEN L

MASTER CERTIFIED MECHANIC
50,192 POSTS

Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.

Was this

answer

helpful?

Yes

Saturday, December 7th, 2024 AT 12:46 PM

KILAMAJARO77

MEMBER
19 POSTS

So having 2 different temperatures like that is normal?

Was this

answer

helpful?

Yes

Saturday, December 7th, 2024 AT 12:53 PM

KEN L

MASTER CERTIFIED MECHANIC
50,192 POSTS

Can you explain a little more what is going on?

Was this

answer

helpful?

Yes

Sunday, December 8th, 2024 AT 9:54 AM

KILAMAJARO77

MEMBER
19 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?

Was this

answer

helpful?

Yes

Tuesday, December 10th, 2024 AT 11:57 AM

KILAMAJARO77

MEMBER
19 POSTS

Bad water pump?

Was this

answer

helpful?

Yes

Tuesday, December 10th, 2024 AT 12:57 PM

KEN L

MASTER CERTIFIED MECHANIC
50,192 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)

Was this

answer

helpful?

Yes

Wednesday, December 11th, 2024 AT 10:03 AM

KILAMAJARO77

MEMBER
19 POSTS

Hi Ken, thank you. Okay, I'll give that a try and get back to you. Maybe Friday.

Was this

answer

helpful?

Yes

Wednesday, December 11th, 2024 AT 4:33 PM

KEN L

MASTER CERTIFIED MECHANIC
50,192 POSTS

Sounds good, have a nice weekend!

Was this

answer

helpful?

Yes

Thursday, December 12th, 2024 AT 12:29 PM

KILAMAJARO77

MEMBER
19 POSTS

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

Was this

answer

helpful?

Yes

Thursday, December 12th, 2024 AT 7:41 PM

KEN L

MASTER CERTIFIED MECHANIC
50,192 POSTS

Yep, it can be just clogged internally which is common.

Was this

answer

helpful?

Yes

Friday, December 13th, 2024 AT 12:42 PM

KILAMAJARO77

MEMBER
19 POSTS

Merry Xmas Ken! I couldn't get those hose clamps off and it was getting colder because I was doing things outside, so I didn't want my hose to freeze up or break, so I gave up. I'm going to have a shop do it for $60 and be done with it. Thank you. Have a Happy New year and if I ever need your help, I'll be sure to reach out. Later on.

Was this

answer

helpful?

Yes

Thursday, December 26th, 2024 AT 11:44 AM

KEN L

MASTER CERTIFIED MECHANIC
50,192 POSTS

Sounds good, the core flush should fix it, Merry Xmas to you as well, let me know how it goes :)

Was this

answer

helpful?

Yes

Friday, December 27th, 2024 AT 10:15 AM

KILAMAJARO77

MEMBER
19 POSTS

Hi Ken, Got the heater core flushed. It took them 3 times plus they had to replace my right actuator, so I now have heat! Better than I ever had! Take care Ken. Thanks for your advice. You're on my speed dial. Later on.

Was this

answer

helpful?

Yes

Saturday, January 4th, 2025 AT 4:00 PM

KEN L