If you encounter AC compressor noise on startup
AC compressor noise on startup—GM has issued a technical service bulletin #07-01-38-010A to address an AC compressor noise on startup. If your AC compressor makes noise 07-01-38-010A, read this article.
2007-2008 Cadillac Escalade Models
2007-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2007-2008 GMC Sierra, Yukon
Equipped With Air Conditioning (RPOs CJ2 or CJ3)
The AC compressors in these vehicles are mounted towards the bottom of the engine. As a result, liquid refrigerant and refrigerant oil can pool in the compressor after shutdown. On startup, the compressor attempts to compress liquid refrigerant and your compressor makes noise and you get AC compressor noise on startup. This is known in the industry as compressor “slugging” and can destroy an AC compressor.
The refrigerant accumulation happens during warm outside ambient temperatures. The noise can sound like serpentine belt or pulley rattle noise, as a belt chirp or as a thumping/grinding noise coming from the A/C compressor at vehicle startup.
GM has issued a software fix to correct the problem. The software cycles the compressor in short burst to prevent the damage and remove the liquid refrigerant. The reprogramming can be done at any dealer or independent shop capable of doing PCM updates.
Be aware that the slugging condition can also damage the serpentine belt tensioner and the serpentine belt. Gates has also issued a technical service bulletin #PA004-14 to address the damage to the belt tensioner caused by slugging.
The Gates bulletin titled PREMATURE TENSIONER FAILURE DUE TO A/C
COMPRESSOR SLUGGING applies to the vehicles listed below:
Chevrolet Avalanche, Express, Silverado, SSR, Suburban, Tahoe, Trailblazer, Envoy, Sierra
GMC Savana, Yukon
Equipped with the 4.3L, 6.0L, or 6.2L engines
The slugging can damage the belt, looking like this:
And the slugging puts so much stress on the tensioner it can damage the unit.
©, 2015 Rick Muscoplat
Posted on by Rick Muscoplat