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Rear A/c Compressor 2000 Yukon Denali

pcourterelle

By pcourterelle
in Ask A GM Technician

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pcourterelle New Member

pcourterelle

Posted
Posted

Hi all.....test drove a 2000 Yukon Denali, has 229,000 KM on it but is in very good shape for it's age, both in and out. On the test drive, I noted that the rear a/c compressor comes on and stays on and is VERY loud when rear air is turned on. No issues with the front air although perhaps not as cold as could be compared to wife's RAV and my 1991 Blazer (I'm sure I'll burn in some eco-hell for preferring 4WD and SUVs but I live in Canada and winter is 8 months long)...

 

It appears the rear A/C compressor is located inside a panel at the back of the passenger compartment. The truck, which was at a used car dealer, had been sitting for some time. I assumed that the compressor would eventually turn off but it never did it just kept cycling and was as loud as my 1/2HP compressor I use in the garage.

 

Also, any comments on older Yukon/Tahoes would be appreciated. Seems there may be issues on the Denali models with towing/transmission and I'm specifically looking at this vehicle for towing (certainly not trips to local Safeway at nearly $1/litre ($4us/gal)....This is a 5.7L V8 Vortec engine with Class IV tow hitch/package....link to the ad below...

 

http://www.canadatrader.com/result/detaili...=calgaryalberta

 

http://www.canadatrader.com/result/detailinfo.aspx?ID=1081580&pgno=1&srt=10&r=calgaryalberta

 

Thanks,

 

p

bill190 Enthusiast

bill190

Posted
Posted

I don't have a service manual for this vehicle, but I can't imagine there would be an A/C compressor inside the vehicle in the rear????

 

Seems to me the rear A/C would use the engine compressor. And the noise would be from something else like a fan motor.

 

To verify this, I tried searching for this vehicle and "rear compressor" and found nothing.

 

You could verify this by looking at the A/C tubing coming from the rear. See if it connects into the front A/C lines.

 

The thing is when the refrigerant is "compressed", it gets hot. Then this heat needs to be cooled. And this would best be done in the engine compartment. So it makes no sense to me that there would be a compressor for A/C in the rear?

 

But you say it sounds like a compressor!

Perhaps an auto leveling compressor for trailer towing and they connected it to the rear A/C circuit?

 

A mystery! ?????

bossier62guy Senior Enthusiast

bossier62guy

Posted
Posted
I don't have a service manual for this vehicle, but I can't imagine there would be an A/C compressor inside the vehicle in the rear????

 

Seems to me the rear A/C would use the engine compressor. And the noise would be from something else like a fan motor.

 

To verify this, I tried searching for this vehicle and "rear compressor" and found nothing.

 

You could verify this by looking at the A/C tubing coming from the rear. See if it connects into the front A/C lines.

 

The thing is when the refrigerant is "compressed", it gets hot. Then this heat needs to be cooled. And this would best be done in the engine compartment. So it makes no sense to me that there would be a compressor for A/C in the rear?

 

But you say it sounds like a compressor!

Perhaps an auto leveling compressor for trailer towing and they connected it to the rear A/C circuit?

 

A mystery! ?????

 

He's obviously referring to the rear fan motor.....the vehicle only has one compressor mounted in the engine compartment.

pcourterelle New Member

pcourterelle

Posted
  • Author
Posted

Thanks all...if it's a fan it's unlike any fan noise I've ever heard...sounds exactly like a compressor cycling and only occurs when rear AC is turned on...there is no discernible difference in noise (as I recall anyway) between the high setting and low setting...a fan issue would likely, although not necessarily, would change pitch/noise level depending on setting no? How accessible is the fan?

 

Will be towing a 3500 GVR trailer to Alaska and back....current hitch on the vehicle, which appears to be factory but I have to double check that against the codes in the glove box is rated 5400lbs...different jurisdictions in Canada insist on different towing capacity....a Class II hitich would be fine in Alberta but BC would require a Class III ect....

 

thanks for all the input, much appreciated...

txab Senior Enthusiast

txab

Posted
Posted

Adding a larger tranny cooler is always a good thing. Completely changing the fluid in the tranny along with the filter. Changing fluids in the diffs and the transfer case. Change the coolant. Check fans or fan clutch for proper operation. Check all belts and hoses. Always tow using the proper gear for the conditions.

 

 

Tranny cooler pic

wcraft New Member

wcraft

Posted
Posted

This sounds like something my Suburban does. If so, my problem is a bad air compressor behind the rear wheel on the driver side. This is used to pump up the air shock absorbers for the Autoride system. Thanks to another person on this board I found a place that sells the compressor for a lot less than the dealer. Mine makes all that noise too, but at least it turns off after awhile. If yours is staying on, the shock absorbers or the air supply hose(s) could be leaking, causing the pump to run forever. Maybe a coincidence that it came on at the same time you turned on the rear air. www.arnottindustries.com

pcourterelle New Member

pcourterelle

Posted
  • Author
Posted

Hi...further to the above...I went for another test drive and it is the fan ... not sure about the fix but will have to look at that later...

 

I took the truck to AMA for an inspection prior to purchase (still haven't bought it) this is what they found...any thoughts, ideas? Big concern is the left front axle seeping as this could be the seal and would require the axle to be removed ect...could also just be the differential plug ???......oil cooler lines on GM products seem a common problem....since I'll be towing in the summer these will need repaired...I've read that GM replacements are not as good as Dorman's? Thoughts?

 

Again, thanks

 

 

2000 GMC Yukon Denali

4x4, 5.3L Vortec V8 engine

228,000 KMs (148K Miles approx)

VIN 1GKEK13R2YR150459

 

AAA inspection noted the following

Oil Cooler lines leaking

Pitman arm is loose

stabilizer bar bushings cracked

front u-joint, rear shaft loose

left front axle seal seeping

pcourterelle New Member

pcourterelle

Posted
  • Author
Posted

Hi Wesley...thanks for the input...I was seriously worried that it could be related to the Autoride system...but I did another test drive and the noise level changes with the setting of the AC in the back....that is, the noise is louder with the fan on high than it is when the fan is on low. The Autoride compressor would be not be related to changes in AC fan settings (God willing)....p

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