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2002 Bonneville stopped cooling

TylerW on Sat June 07, 2008 10:16 PM User is offline

Year: 2002
Make: Pontiac
Model: Bonneville
Engine Size: 3.8L

Hey everyone, new to the forums.

I have a couple problem vehicles, and this question will pertain to the first, a 2002 Pontiac Bonneville SE with single zone HVAC:

I purchased this car last year during cool weather and never really thought to check the AC...it being a newer car I just assumed it was fine.

Well, when the weather warmed up, I began to use the AC and noticed that things were not up to par.

At first, the air from the vents would be cold at idle speeds and low speeds, but warmed up at higher speeds such as highway driving.

I lived with that for a while, then, the air from the left-side vents stopped getting cold at all, but the right side air flow remained "cool"..not cold.

Now, a couple weeks later there is no cooling in the interior of the car whatsoever.

I believe this car has a non-cycling V5 compressor.It does come on and stay operating whenever the AC is selected.

The low-pressure line back toward the firewall does get cold and drip condensate when the AC compressor is in operation.

I've checked the blend door motor to confirm operation and that is not the problem.

I apologize that I have not yet gotten pressure readings...a manifold set will be purchased in the very near future.

I did use the gauge on the low-side that came with a charge kit long ago and observed about 26 psi during compressor operation.

Thanks for any advice you can give me.

Tyler


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93 Dodge Ram
02 Bonneville
78 LeMans Coupe
78 Century wagon

GM Tech on Sat June 07, 2008 10:24 PM User is offline

typical low charge scenario- find and fix your leak and evac and recharge

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

TylerW on Sun June 08, 2008 7:05 PM User is offline

No, I'm pretty confident it's not a charge problem because it has PLENTY of refrigerant in it.That's the quick answer everyone gives.

The person with the 2003 S10 that posted got plenty of good advice regarding his problem which is similar to mine, but let me repeat, the low side line on my vehicle is getting COLD quickly.

I'll get the gauges put on it.

-------------------------
93 Dodge Ram
02 Bonneville
78 LeMans Coupe
78 Century wagon

TylerW on Tue June 10, 2008 9:11 PM User is offline

Well, let me apologize for jumping to conclusions.

I have to admit that these constantly-on type compressors are throwing me for a loop.

I will add a bit of info..today I left the AC on for about a 30 minute drive, and when I arrived at my destination, I popped the hood and felt the low-side line, which was very cold.

While i was standing there, I heard a clack from the compressor, followed by another one, only not near as loud.After that, the low-side line started warming up.

So, do these type compressors remained engaged even if the refrigerant is low? If that's the case, how does it not burn up?

I assume the clack I heard was the internal valve in the compressor stopping the charge flow...

I try to think things through logically and that's why it's grating on me that I can have a cold line to the firewall but never any even mildly cooled air out of the vents.

With the guages in place, what kind of operating pressure should I want to see?

Thanks guys...

-------------------------
93 Dodge Ram
02 Bonneville
78 LeMans Coupe
78 Century wagon

GM Tech on Tue June 10, 2008 10:39 PM User is offline

How can you assume that the charge level is okay?? How do you ascertain it has "plenty" of refrigerant in it- did you just weigh the refrigerant in today? There is only one way to know for sure how much is in it- and that is to extract and weigh it-- pressure will not tell you much- oh yeah there are a few basics- but for you to say the charge level is not the issue tells me you are not familiar with a/c-- static pressure is the same for 8 ounces or 80 ounces- refrigerant is a condensible- not a compressable like air-- more refrigerant does not mean more pressure statically.....

The V-5 variable stroke compressors will run with as little as 4 ounces of refrigerant- they won't cool, but they will run-- they don't have "low" charge protection- they have "no" charge protection- - The compressor will be running at minimum stroke because your suction pressure is extremely low- so chances of burning it up are lessened. A good running V-6 system on high blower at 80 degf ambient would be about 30 psi low and 175-200 psi high. Play the odds- 65% of what I see have a dramatic loss of refrigerant due to a leak- in your case the compressor shaft seal is highly suspect- followed very closely by the compressor body o-rings... Take ny word for it- I've seen a bunch....prove it to yourself by adding a can or two- watching very closely the high and low pressures- see if it starts cooling after about 20 ounces added-- then recovery it abd find and fix your leak...

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

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