AC on, it suddenly began blowing hot air

Tiny
SILVEREDGE77
  • MEMBER
  • 2010 CHEVROLET SILVERADO
  • 4.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 96,000 MILES
Driving along with AC on, it suddenly began blowing hot air instead of cold air. Did a coolant recharge per the directions. Still blowing hot air, some of the lines around the AC are cold to the touch and the compressor is running all the time. What should I look at next?
Thursday, August 9th, 2018 AT 2:17 PM

21 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
This sounds like the compressor has gone out or the system is low on charge or a fuse is bad, these videos and guides can help us fix the problem with diagrams below to show you how on your car. I have included (below) the air conditioner wiring diagrams as well so you can see how the system works.

https://youtu.be/4UjfQKvrB6Y not working

and

https://youtu.be/uZrQCGwXfek recharge

and

https://youtu.be/yrhWKlQEPWw leak detection

and

https://youtu.be/4EqdrBVb0sY vacuum and recharge

and

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Let us know what happens and please upload pictures or videos of the problem.
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Thursday, August 9th, 2018 AT 2:38 PM
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 2007 CHEVROLET SILVERADO
  • 36,000 MILES
When ac is turned on, it blows "hot" air. I pushed the compressor button in and it stays lit. I have the slide control all the way on blue for cold, nothing but hot hot air.
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Friday, April 30th, 2021 AT 2:11 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check freon level first it may be low if compressor is running then check actuator in heater as one controls temp, remove hvac fuse for 60 seconds then reinstall with key on. It may reset after a minute if not the actuator may not be working. Generic pic included.
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Friday, April 30th, 2021 AT 2:11 PM (Merged)
Tiny
ZACH870
  • MEMBER
  • 2 POSTS
  • 2006 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
So the A/C normally works really good blows hard and cold, but for the second time in two months it has went from blowing cold to hot while driving. If I stop and turn it off then turn it on, it will go back to blowing cold.

What gives, I was thinking one of the actuators maybe?
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Friday, April 30th, 2021 AT 2:11 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
Hello,

Yep the blend door actuator go bad in these trucks, here is an excellent guide that will show you what you are in for when doing the job.

https://www.2carpros.com/articles/replace-blend-door-motor

Please let us know what happens.

Cheers, Ken
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Friday, April 30th, 2021 AT 2:11 PM (Merged)
Tiny
ZACH870
  • MEMBER
  • 2 POSTS
Thanks Ken, I just ordered the part will be changing it asap. Alabama is too hot ro be hanging my head out the window stuck in traffic
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Friday, April 30th, 2021 AT 2:11 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
Lol yep no need for that.

Please let us know how it goes.

Cheers, Ken
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Friday, April 30th, 2021 AT 2:11 PM (Merged)
Tiny
PEGASUS1
  • MEMBER
  • 6 POSTS
  • 2004 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 105,000 MILES
Even with outside temp of 71 degrees truck was blowing hot air this morning. Original battery gave up Friday and replaced it Saturday
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
This sounds like the temperature actuator is not working here is a video and guide to help fix it.

https://www.2carpros.com/articles/replace-blend-door-motor

and

https://youtu.be/Eqf-H3COtSo

Is the AC compressor working? This guide should help us fix it

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Please run down this guide and report back.
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
PEGASUS1
  • MEMBER
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Best I can tell. I checked it this morning and it is not making any funny noises, but I can't tell if it the clutch is engaging.

Even with the vent on it was blowing hot/warm air. Outside temperature this morning was 71 degrees.
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
I think you have a problem with the blend air door.
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
PEGASUS1
  • MEMBER
  • 6 POSTS
I reconnected the battery and every thing is working like it used to.
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
That is good. If you have problems in the future, let us know.
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
ROBERTBARNES62
  • MEMBER
  • 83 POSTS
  • 2003 CHEVROLET SILVERADO
  • 6.0L
  • V8
  • AWD
  • AUTOMATIC
  • 150,000 MILES
One day the AC was working great and then the next day it was blowing hot. The compressor is cycling on and off. I checked the inlet blend door actuator and it seems to be working, I say this because as I turn it from hot to cold I can feel the actuator turning when I place my finger on it. I jumped the low pressure switch and still no cold air. The compressor is clicking on and off, not sure if it is doing it too fast or not because I am not sure how fast that cycle is suppose to be. I put a gauge on the low side, the only gauge I own is from one of those cans you buy from the auto part stores, and the gauge fluctuates back and forth from side to side. I also reset the AC control module by taking out the fuse and following a outlined sequence of turning the key on and off. Also, last year the system was vacuumed down and the orifice tube was replaced. Not sure if this will help but at the accumulator one line is cold and the other is not.

I need some guidance as to what could be the problem. I would like to try to fix it on my own if I can so I can save the money of going to a shop.
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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You have a large tube exiting the fire wall and then headed to the rear of the compressor. With the engine running and the system on use your hand and see if the tube is cold at the fire wall. This will help us see if it is a blend door problem or a compressor issue.

Here is a diagram (below) and a guide that can help:

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Please let us know what happens and upload pictures or videos of the problem.

Cheers, Ken
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
ROBERTBARNES62
  • MEMBER
  • 83 POSTS
I ran the truck and turned the A/C on and have attached a picture of the lines and where it was hot and where it was cold. I hope this helps you help me. Thank you
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
Thanks for the images :)

Yep a classic case of the system being low. I suggest you using a gauge set though so you can see what the high side is doing which is more important.

Check you think guide.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Please let us know what happens.

Cheers, Ken
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
ROBERTBARNES62
  • MEMBER
  • 83 POSTS
So does this mean there is a leak in the system? I know the system was vacuumed down and recharged last year to replace the orifice tube. It should not have to be added to every year does it?
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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It does sound like you have a leak because you should not have to recharge it more than every other year.

Here is a guide to help us find it so we can get it fixed:

https://www.2carpros.com/articles/air-conditioner-leak-detection

Please let us know what you find.

Cheers, Ken
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Friday, April 30th, 2021 AT 2:13 PM (Merged)
Tiny
ROBERTBARNES62
  • MEMBER
  • 83 POSTS
Hello, sorry it took so long to reply back but I did find the problem. There was in fact a leak. Seems that when it was serviced some dirt got into the valve where you add refrigerant. I noticed there was a puddle of what looked like green fluid. I contacted the ac shop and the guy had me come by and said yep that's where dye was added and is leaking out of the system. He put a new valve in and charged it for 30 bucks. Blowing cold as ice now. Thank you for all your help!
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Friday, April 30th, 2021 AT 2:13 PM (Merged)

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