2021 with Intermittent AC Cooling Issues

[tjonesdfw]

5.3 Sierra with approximately 80,000 miles had a radiator replacement about 6 months ago which required pulling the AC condenser and a vacuum and recharge on the system.  AC cooled fine until about a month ago, when it would suddenly start blowing lukewarm air for 5 minutes at a time at various points throughout the day, then suddenly resume cooling again.  Sometimes its when stopped at an intersection and other times while moving.  I've read about the internal electronics in the compressor going bad on these trucks and not cycling properly, but sounds like many dealers just chase AC issues with a parts cannon.  Also wondering if they charged it correctly when the radiator was replaced.   Is there an easy way to see if these electronically driven compressors are engaging properly, or to check for freeze up, etc.?  Dealer usually wont do much unless they can replicate or I can show them a video of what's going on.  

[silveradosid]

it does sound like freeze up, check the drain and also check the cabin air filter to see if it is plugged

[KARNUT]

I had a strange problem with my Avalanche. Yearly once the temperature started getting hot. It would freeze me out going to my walking trail about 8 miles. Nothing but hot air going home. My machanic would put the Freon in the machine vacuum the system. No leaks put the Freon back, good for the year. My brothers truck wouldn’t work at all until he did the same procedure. I believe he finally changed the expansion valve to solve his problem.

[GMCustomerService]

On 7/15/2026 at 9:35 AM, tjonesdfw said:

5.3 Sierra with approximately 80,000 miles had a radiator replacement about 6 months ago which required pulling the AC condenser and a vacuum and recharge on the system.  AC cooled fine until about a month ago, when it would suddenly start blowing lukewarm air for 5 minutes at a time at various points throughout the day, then suddenly resume cooling again.  Sometimes its when stopped at an intersection and other times while moving.  I've read about the internal electronics in the compressor going bad on these trucks and not cycling properly, but sounds like many dealers just chase AC issues with a parts cannon.  Also wondering if they charged it correctly when the radiator was replaced.   Is there an easy way to see if these electronically driven compressors are engaging properly, or to check for freeze up, etc.?  Dealer usually wont do much unless they can replicate or I can show them a video of what's going on.  

We understand that intermittent AC concerns are inconvenient, @tjonesdfw, especially since they often do not show themselves when we want or need them to. We would like the opportunity to learn more about your experience with your Sierra and explore the best path of assistance moving forward. To begin, please visit: https://s.gmc.com/support-request  and fill out the support request form with all pertinent details. This form helps our team gather the right information and ensures your request is routed appropriately.

[tjonesdfw]

According to the dealer it’s an internal leak/failure of the compressor.  Again, another failure that shouldn’t happen at only 5 years and 80k miles.  For some reason the compressors must be hard to come by right now, because the truck’s been at the dealer almost a week and they just located a compressor at another dealer several states away today.  We’ll see if this fixes the issue.  

[davester]

3 hours ago, tjonesdfw said:

Again, another failure that shouldn’t happen at only 5 years and 80k miles

google "bathub failure curve".

Basically, any part of the vehicle can fail at any time.  It starts off as being more likely (early failure), then the failure rate goes down (but does not go to zero), then it goes up over time because it wears/ages out.