Found 1 more
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Date: October 06, 2009
Subject: Air Conditioning (A/C) Compressor and/or Serpentine Belt Noise at Vehicle Start-up (Reprogram Powertrain Control Module (PCM))
Models:
2007-2008 Cadillac Escalade Models
2007-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2007-2008 GMC Sierra, Yukon Models
Equipped With Air Conditioning (RPOs CJ2 or CJ3)
Supercede:
This bulletin is being revised to update the Condition and Correction information. Please discard Corporate Bulletin Number 07-01-38-010 (Section 01 - HVAC).
Condition
Some customers may comment on air conditioning (A/C) compressor slugging and/or serpentine belt or pulley rattle noise at vehicle start-up in warmer outside ambient temperature conditions. Others may describe the noise as a belt chirp or as a thumping/grinding noise coming from the A/C compressor at vehicle start-up.
Cause
This condition may be caused by the A/C compressor trying to move liquid refrigerant through the system.

 

Serpentine Belt Noise at Vehicle Start-up

No belt on a hybrid AC compressor.

 

My 2009 hybrid Tahoe has had a weird noise lately that I have not been able to nail down, It has never had this noise before that I have noticed.

It has been extraordinarily hot(110 plus) and humid here in the past few months, I suspect the noise has something to do with the AC.

The noise is a deep hum, sort of like a fan, but it has no connection to engine RPM or throttle. it only happens from 20-35 MPH, it's a distinct deep humming noise, only when the ICE engine is engaged.

I have several large diesel trucks and it almost sounds like the fan clutch fully engaging on a large Diesel engine. On a large Diesel engine(11-16 liters), when it needs to be cooled at slow speeds the fan can sound like a tornado, very similar.

 

The AC compressor is 300V system driven. It runs at speeds and loads commanded by the AC computer. The compressor makes a buzzing sound near the right front wheel forward. In Auto-Stop and slow/parking lot speeds the compressor may slow down to not be too noisy. You will feel changes in the AC air temperature when this happens. Then as the vehicle speed increases the compressor may go to full power and you may be hearing that.

Your main engine cooling fans are 3-speeds. They may be contributing. The dealer scan tool can read and command fan speeds.

The dealer scan tool has the ability to read compressor speed and the refrigerant pressures. The scan tool has the ability to command various compressor speeds.

A clever tech could help here.

 

Any updates from the OP? I have my Wife's Tahoe Hybrid (08) in the shop right now with this issue. They just called and gave me the same listed TSB but I just wanted to make sure nothing else was done.

They are making sure the refridgerant charge amount is at the right levels, so I'm hoping this maybe lessens the amount of times this happens. I can say on any day that is in the high 90's and above, we have to turn off/on just the AC every 5-10 mins...

It may not be an issue for GM right now but if I have to turn the compressor on/off that many times during an Arizona summer, that has to lessen the life of the compressor really quick imo...

 

I have a 2008 Yukon, my problem begin when a previous year I had a freon leak, I took it to the dealer 2 times, the fisrt to put the die on, and to re-charge the freon, the 2nd time I brought it in because the freon went out again, at that time the compressor staring to make like a electric motor was on, so I told them, please change the compressor because it's making a lot of noise, but they didn't wanted because it was nothing wrong whit it, so I let it go, and then brought it back for something like the stalling on my wife all the time, and I told them one more time, because it was louder, and that's when they replace it under my warranty.
By the way I still have issues whit stalling and now I have a code about a cat converter error.