If it is only staalling when the AC is on, then you have a problem. Mine was doing the exact same thing, running fine but idling down and stumbling but not actually stalling every time I had the AC running and the truck was sitting still idling. It was doing that for about 2-3 months. Then it started chattering (sounded like a mini jackhammer) upon acceleration. I saw that the AC tensioner was broken and wobbling really bad so I changed it. The next day, that tensioner broke. I got another one and that one broke too. Then I found a paper in the box that said "WARNING, Failure to replace a faulty AC compressor will result in failure of new tensioner and/or belt. lease refer to General Motors TSB# 03-01-38-019A " I have now taken my AC belt off until I can get my compressor replaced. I have read stories on other forums about the belt getting destroyed and hitting on the transmission cooler lines (which run right under the AC compressor) and ripping the lines apart and having a bad trans fluid leak. So far I got 5 estimates to have y AC compressor replaced, and the cheapest price was 1100$ The compressor alone (if you have the rear AC like I have) is anywhere from 350-500 bucks. Plus you have to replace the drier and the orifice tube as well. When I have enough money for the parts, I will be replacing everything myself.
And here is what the service bulliten says:
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Condition
Some customers may comment about an underhood rattle noise heard on acceleration or a sudden loss of A/C system performance.
Cause
This condition may be caused by liquid slugging of the A/C compressor. This condition may cause an internal failure in the A/C compressor. The serpentine belt tensioner and serpentine belt may also be damaged.
Correction
Technicians are to check the A/C system performance and compressor operation using the following repair procedure:
Open the hood and inspect the A/C compressor for damage and to see if the compressor is seized. Verify that the serpentine belt is not damaged or missing. If the A/C compressor is seized, proceed to step 5.
Perform the A/C System Performance test. Refer to the Heating, Ventilation and Air Conditioning (HVAC) section of SI. Correct any performance concerns or refrigerant leaks that are found.
Inspect the vehicle for other possible sources of A/C compressor noise or performance concerns. Refer to Corporate Bulletin Number 01-01-38-013 for more information.
After all other possible sources of A/C compressor noise or performance concerns have been eliminated, only then should the A/C compressor be replaced.
Remove the A/C compressor. Refer to the A/C Compressor Replacement procedure in the HVAC section of SI.
Inspect the transmission cooler lines for damage due to contact from the serpentine belt. Replace the transmission cooler lines if necessary.
Install an inline A/C system filter. Refer to Corporate Bulletin Number 01-01-38-006C for more information about A/C system flushing and filter installation procedures. An A/C system flush is not to be done unless prior authorization is given by the GM Area Service Manager (in Canada, the District Service Manager).
Install an A/C Suction Screen. Refer to Corporate Bulletin Number 01-01-39-003A for more information about A/C suction screen repair recommendations and procedures.
Install a new A/C compressor. Refer to the Compressor Replacement procedure in the HVAC section of SI.
Install a new orifice tube for the front A/C system. Refer to the Expansion (Orifice) Tube Replacement procedure in SI.
If the vehicle is a 2003 model year Chevrolet Express or GMC Savana van, the vehicle may require a new accumulator. Refer to Corporate Bulletin Number 03-01-38-016 for more information. This bulletin refers to an updated design accumulator that may improve the performance of the A/C system.
Install a new serpentine belt tensioner and serpentine belt if they have been damaged due to A/C system slugging or an A/C compressor seizure. The serpentine belt tensioner may have broken stop tabs and/or a missing front cap.
Verify proper operation of the A/C system.
Parts Information
Refer to the GMSPO parts catalog for the latest service replacement compressor part numbers.
Part Number
Description
Qty
89016656 (*A/C Delco Part# 15-10413)
Universal In-Line A/C Filter
1
Parts are currently available from GMSPO.
*This filter may also be purchased through your local A/C Delco distributor.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
D4440
Compressor Assembly - Replace
Use published labor operation time
