2001 GP GT 3.8 A/C Problem

I have a 2001 Gr Prix GT 3.8. I recently had the upper and lower intake manifold replaced (common problem in these cars)at a Pontiac dealership. After the work was done, I noticed the heat and air was blowing only out the defrost vent near the windshield. I took it back, lo and behold, the mechanic knocked loose the vaccuum hose. They "fixed" their mistake and all was well. Until it got hot out a couple weeks later, and I turned on the A/C and while it was blowing air, it is NOT cold air. Given the dealership's admitted prior mistake and the fact I have had NO problems with my AC until they worked on the car, I figured they did something to it while working on the intake manifolds. I took it back in, and they did a dye test and some other test to see if there was a leak, because there was no refrigerant in the system at all now. They could NOT find a leak anywhere. I suggested the problem resulted from something they did or didn't do while replacing the intake manifolds, but the dealership insists not, that they did NOT have to touch the A/C system nor did their work affect it in anyway. I've talked to a lot of people who all agree they could NOT have replaced the manifolds without it affecting the A/C. I'm trying to get a certain answer so I can take this further and have the dealership be held responsible if they indeed are. Any thoughts?

Welcome to AF.

Although I hate to I would have to agree with the dealership in your case. Last time I checked no A/C components are affected or touched when doing a UIM/LIM job. I can see leaving the accessory vacuum off inadvertantly located on the backside of the LIM.

If the refrigerant charge is zero then there is a big leak and I find it hard to believe it cannot be found. Commom problem areas for leaks are the lines, compressor, accumulator or condensor.

You can troubleshoot the A/C system DIY or take it to a shop that specializes in A/C diagnoses and repair. IMO dealerships leave alot to be desired in A/C work.

Thanks for the info. It is holding a slight charge. When my dad and I tried to charge it with stuff I bought from Auto Zone, it got cold and stayed cold for about 20 minutes, then lost it again. Tried it again only this time with a pressure gage, and while the gage showed 30 PSI, it would not go above that nor would it get cold again. It was coldest out of the left side passenger vent, and hotter out of all the rest, which I thought was odd. I was told the compressor is engaging. Dealership said could be a pinhead size leak and wanted to recharge it. Without them finding the true cause, I said no.

Since the leak is not readily apparent, I would guess it's in the condenser area (the big finned piece in front of the radiator). It may have gotten hit by a stone or other debris beteween when you had the UIM repaired and now. I agree with bnaylor that there are no A/C related parts anywhere near the UIM and the dealership is innocent here.

Thanks for the info. I should probably mention that when the manifolds were replaced, they also worked on and replaced the blower motor resistor as levels 1 and 2 were not working at all. When this part of the work was done, could it have affected the A/C system at all?

I doubt it. The BMR is in the heater box by the blower motor. It's no where near anything that could create a freon leak.