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97 Grand Prix - only blows cold on Left Side

Anonymous on Thu August 28, 2003 10:32 AM User is offline

Year: 1997
Make: Pontiac
Model: Grand Prix
Engine Size: 3.8L

The compressor on my car recently went bad. Symptom was less cooling and the left side vents were noticeably warmer than right side. Lost much compressor fluid (oil) from the dying part.

Local shop replaced compressor, recharged and all was well for a week or two...

Then the left side stopped putting out cool air. It now takes quite some time for the car to cool down. The left side vents seem to have a tiny bit of chilled air mixed with either inside hot air or outside hot air (I'm in Dallas and it's 100). Once the car cools down (15-20 mins) the left side seems fairly close in temp (based on my scientific hand measurement).

Same local shop says "we didn't touch that part of the system. you most likely have a mixer problem. we will have to pull the Dash (8 hrs, $750)". Needless to say, I haven't exercised that option yet.

I've got the front (partial) part of the dash pulled but haven't figured out how to get the rest off yet to get to the mixer. I'm mainly wondering if this is a path to follow and what will I find when I get to the mixer (I'm assuming this is where the exchanger is). I can't seem to find any readily available self-repair books for this car either.

Anyone seen something like this and have thoughts/history on what was the resolution?


Mitch on Thu August 28, 2003 10:47 AM User is offline

Do you have separate controls for the driver and passenger temp?

That can make a big difference in the troubleshooting and diagnosis.

The Helm factory service manual has all the info you need. I have one for a 2001 GP. Unfortunately, list price is about $120.

Sometimes you can get used manuals cheap ($20-50) on e-Bay.

There is a possibility that you now have a refrigerant leak as a result of the repairs not being done correctly and the system is not cooling properly.

Anonymous on Thu August 28, 2003 10:51 AM User is offline


NO dual controls

I'll sniff around for the manuals you mention on ebay - good idea!

Mitch on Thu August 28, 2003 10:56 AM User is offline

With no dual controls, my first guess is that you are low on gas. I would take it back and have them check the charge level.

GM Tech on Thu August 28, 2003 1:17 PM User is offline

Don't pull the dash! You are low on refrigerant- W-cars do this- cool on one side better than the other when there is not enough refrigerant-- fix your leak- probably the shaft seal then recharge to spec then it will cool properly....

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......

Anonymous on Fri August 29, 2003 9:18 AM User is offline

I'm taking this thread to my shop and see if we can get this resolved. I'll circle back after I've got more news so others can see the final resolution if we find that out that I'm low on refrigerant.

Thanks again to Mitch and GM Tech for pitching in; you may have saved me a ton of money!

Dougflas on Fri August 29, 2003 11:36 AM User is offline

I saw this same problem on another forum. Same fix...low on refrigerant.

Anonymous on Wed September 03, 2003 12:31 PM User is offline

So Here's the Result:

Took car back to shop. They continued to be dubious of my thoughts and the thread from this group.
They check the refrigerant level and lo-and-behold - it is low! So ya'll are right, low Refrig on this car caused the air to blow cold only on one side. Unfortunately, these guys persisted in claiming I have a blower box restriction. They nut case said it would still blow warm on the other side; when I started the car up it chilled just fine on both sides. So these guys get no more of my business; very shady, telling me I need to spend $800 to pull a dash when the refrig is low. I grilled them on whether they had checked refrig. levels the last time I took it in and they claimed they had. I'm really glad I got suspicious and found this forum; I would have been taken for $800 when the root cause is elsewhere!

They asked if my car had overheated. I said no. They claimed that the refrigerant is low because the car overheated and the safety valuve on the compressor leaked refrigerant to protect the system.

Not sure I totally buy this; the car has never overheated. However, I did have a leaky water pump so it's feasible that it got a bit warmer than normal but never exceed 210 degrees, based on the in-dash thermo. Now I've fixed the WP and gotten the system recharged and we'll see what comes of it. Is there anything else that could cause an A/C system to vent refrigerant thru the safety valve (they saw dye at that part of the system).

Another local shop was dubious of the claim that overheating could cause the system to lose so much refrigerant that it won't cool. And my brother has experienced this very thing on his Honda when it overheated.

Thanks again for the help and advice.


Mitch on Wed September 03, 2003 1:44 PM User is offline

You probably need a new shop. Your car has a high pressure cut out set at about 430 psi and the relief valve is set at 525 psi, so it should never open unless there is a mechanical problem with the relief valve going off too low (really, really rare) or an electrical problem and engine overheating at the same time. Possible, but not probable.

Did the same shop replace the compressor? You may have had the usual GM compressor seal leak and what you are seeing now is residual oil from the old compressor. If they did charge it properly the first time, you still have a leak.

Best scenario would be that the original compressor seal was leaking, the new compressor fixed that, but the shop charged it incorrectly, and now with proper charge it will be OK.

Worse scenario is that you never needed a new compressor and the problem that was diagnosed as a bad compressor still exists and needs to be repaired.

Worst scenario is that the misdiagnosed leak is in the evap core which means pulling the dash, but not for the reason stated by the shop.

More bad news is that a $20 seal may have fixed your original cpmpressor if it was leaking from the front seal. But, most shops are not into replacing seals these days, only replacing complete compressors.

Dougflas on Wed September 03, 2003 4:47 PM User is offline

Have you been talking to GEICO?

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