Thread: AC Troubleshooting

I have a 1997 grand prix Se with 3.8 engine. The AC was cool but not cold. So I just replaced my AC compressor, dryer/accumulator and the orifice tube and all associated o rings today. I put a little PAG oil on the o-rings and used PAG 150 oil to fill compressor with 8 oz. I installed a new compressor not a rebuild. My pressures before were reading 45-50 and 150 psi on the high side before. My old orifice tube was plugged up and had some metal in it. I did flush the system out pretty well and ran compressed air through it all before putting it back together. After vacuuming system down to -25 inHg for 15 minutes and recharging with about 2 Lbs refrigerant I am still at the same pressures. Now on a 90 degree day my pressures didn't change and I am only getting 70 degree vent temps. I have also pinched off my heater hose to rule out heat from the coolant as this has helped in the past. My condenser is a little beat up would this be the cause of problems?

What should I do next?

One, you should have pulled vacuum longer. I would recommend 1 hour minimum, and then let the gauges set to verify no leaks.

two, how much volume does the system call for? Did you weigh it in? How do you know you have about 2lbs? If you do not have enough, you will not get enough cold liquid into the evap.

three, your high side still seems a little low. I would expect them to be slightly higher.

is your ac machine a small vacuum pump? I have a pretty nice robinair pump, and i still let it go for over an hour when i redid my wifes car. a little overcharge may not be a bad thing, but a little undercharge could kill the capacity of the system. it is important to accurately weigh the charge in.

I used a new robinair machine at work to pull the vacuum. I used my own refridgerant... 2 1/2 12 oz cans separate from the robinair machine. The sticker under the hood says my system holds 1.88 oz.

Just a follow up for those searching old threads. I can't remember what exactly solved it but I do know that I replaced the temperature door actuator and I am pretty sure that solved the problem.