Recent purchase- ‘11 Silverado- A/C question

[bamafan76]

Hello again! After a couple year hiatus, I’m back to GM after purchasing a 2011 Silverado 4.8L V8. It is a one owner, 76k miles, overall great condition. It has the common issues, a crack or two dashboard and it had code P0573 when I bought it which I’ll fix. What I didn’t know until my 2 hour drive back home was an AC issue. After about 30-45 minutes into the drive, the air flow tremendously decreased despite turning the fan on high. I turned it off for about 10 min., turned it back on and worked a bit more and then did t again. When I got home I immediately popped the hood, saw the accumulator frozen over. I haven’t checked pressure, but the compressor does cycle. I also read it could be the evaporator temperature switch. I also found it odd there is no cabin air filter which also makes me wonder if the evaporator is dirty. Any insight would be greatly appreciated.

 

 

Edited May 11, 2023 by bamafan76
Wording

[Jworks]

Have you tried adding in refrigerant?....If you have a refrigerant gauge.  I "think" its R-134A

Edited May 11, 2023 by Jworks

[swathdiver]

No cabin filter but you can add it.

 

You need to get a bi-directional scan tool on it that can read BCM codes.  More than likely, your AC refrigerant is just fine and you have some actuators that need replacing.

 

Use GM OE only, buy once, cry once or you'll be doing it again in short order.

[dna9656]

"Buy Once, Cry Once. "Never heard that one! I heard "Buy Cheap You Buy Twice."

[bamafan76]

Thanks for the replies. The dealership I bought it from is making it right even though it was a “as is” purchase by taking a look at it and if they can’t resolve will send it to Chevy dealership. I’ll update on their findings once I get it back.

[Chris krum]

My 12 Sierra has been doing this for a few months, i just got on here to check for advice. It seems like it gets worse when it idles but it will do it when i'm driving interstate also. Any advice would be great, I have 377,****** miles on it and i'd like to keep it for much longer.

[Chris krum]

21 hours ago, swathdiver said:

 

 

More than likely, your AC refrigerant is just fine and you have some actuators that need replacing.

 

 

can you elaborate on this a little?

[Chris krum]

I have noticed that the silver canister up near the fire wall sweats big time. I've checked the pressure a few times and the pressure is good. but it will start blowing warm and it will stop blowing as hard.

[redvett]

Replace the cabin filter before you do anything else.

[Chris krum]

7 minutes ago, redvett said:

Replace the cabin filter before you do anything else.

mine does not have a cabin filter.

 

found this

 

 

[bamafan76]

On 5/11/2023 at 2:07 PM, swathdiver said:

No cabin filter but you can add it.

 

You need to get a bi-directional scan tool on it that can read BCM codes.  More than likely, your AC refrigerant is just fine and you have some actuators that need replacing.

 

Use GM OE only, buy once, cry once or you'll be doing it again in short order.

Is there a scan tool recommendation that also won’t break the bank?

[swathdiver]

On 5/12/2023 at 12:34 PM, Chris krum said:

can you elaborate on this a little?

 

The HVAC system is controlled by 4 actuators.  One of them controls whether fresh air is allowed into the cab or not, or just how much according to the computer.  Another one controls which vents the air comes out of.  Then there are 2 actuators that control the temperature for the driver and passenger side.  As these wear or when teeth break, they do not get into position like they're supposed to and hot air can leak into the cab when none is desired.  Unlike the old days, hot air is made by the system continually and "blended" in with the cold air to make the desired temperature.

 

On 5/13/2023 at 11:08 PM, bamafan76 said:

Is there a scan tool recommendation that also won’t break the bank?

There's going to be an outlay for any decent tool which will pay you back in spades because of the time and money you save on diagnosing and making repairs later on.  A Tech-2 is about $350 which is a bi-directional scan tool that can talk to just about every component in your truck, engine, brakes, radio, AC, windows, lights, etc.

 

In this case, it can read the internal BCM codes and tell us which actuators failed and why, perform tests on the other ones, command them into position and such and then when the new ones are installed, perform a proper calibration.  This would cost hundreds of dollars at a shop.

[Chris krum]

So after thinking about it. When I’m driving down the road, I have very cold air and then randomly it will get warm and muggy and then 5 to 10 minutes later it might get cold again.  Are y’all saying that those flaps will randomly open and close? I don’t know why they would do that…. BUT I did buy 2 actuators and Fiona replace them since I’m slow at work. I hope this works and it’s not a AC component. 

[Chris krum]

Replaced both! Will know in a few days if that was a fix.

[bamafan76]

On 5/12/2023 at 6:31 AM, bamafan76 said:

Thanks for the replies. The dealership I bought it from is making it right even though it was a “as is” purchase by taking a look at it and if they can’t resolve will send it to Chevy dealership. I’ll update on their findings once I get it back.

As an update, I got the truck back today and no problems with the AC on the 2 hour ride home. They replaced (which is what I expected based on research) the evaporator temp sensor.