A/c Compressor Startup Noise On Gmt900 Sierra

saxdogg · October 22, 2008

Hey guys,

I know of the TSB that describes a start-up noise with A/C compressor on the 07-08 GMC Sierras, etc. when the temperature outside is above 95 F. The TSB called it a "refrigerant hammering" sound if I remember it....it sounds like an air compressor in your shop to me, but only does it when the truck is cold on an intial startup when it's super hot.

Anyways, my dealer performed the TSB, which is only a software update, and it did not fix the problem. Now they want to try and reproduce it and probably just throw parts at it since they really don't have anything further to go on...it is too random for me to give it to them to let sit overnight and try once in the morning and besides, it's not warm out anymore anyways... the a/c has always worked fine, it's just annoying (and embarassing!) on a new truck.

My question is, have you techs found a solution or heard of this? What has fixed it if anything?

JP

Alljackedup408 · October 24, 2008

damn.. yeah im sittin here at work on the computer... i just looked throught service info on gmglobal.. ive never seen that issue in my shop... it says the cause is its moving liquid refridgerant through the compressor... and to reprogram the pcm.. like you did.

mmm...i dont know.. maybe suggest a ac refridgerant flush... recover it all..and stick in the right ammount of refridgerant and oil. my best guess..mention that to them.. see if they bite.

minibike132 · November 6, 2008

thanks for the reply ---

lemme ask you this instead...if it's just "liquid ref. moving thru the compressor," is that bad? I mean, it works fine, just periodically annoying ...

I don't want them to start guessing if you know what i mean...

JP

Sorry JP I just got your message. I have never had this issue when cold only either.

saxdogg · October 25, 2008

thanks for the reply ---

lemme ask you this instead...if it's just "liquid ref. moving thru the compressor," is that bad? I mean, it works fine, just periodically annoying ...

I don't want them to start guessing if you know what i mean...

JP