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AC Problem

What would cause the low side pressure on my AC system to be too high?

System is overfilled or contaminated?

It’s a 97 Saturn SL1 with 240,000 miles so can’t be overfilled. Last summer the AC worked, but not real well, this summer not at all. I checked that I have power to the compressor and it does run (clutch kicks in). I assumed it would be low on freon, but when I connected the guage it hit the red zone! I’m thinking maybe the filter/seporator is plugge? If I can’t fix it myself relatively cheaply, it’s not worth spending too much money on.

Any ideas?

It helps to know what the high side pressure is but odds are you have a stuck expansion valve.

Anything I could do to fix this? Like bleeding pressure off of the system, or is this something I could replace myself?

The low side pressure is close to the temperature (in farenheit)of the air blowing across the evaporator. So if the low side is high you will not get cool air out your vents. You need to test with a quality set of AC gauges send us back readings of both high and low side,outlet temp and is the compressor cycling excessively. IMHO only a small portion of AC concerns get “fixed” (that is concern resolved for good with standard system performance)cheaply. People will pay enormous sums of money to get that cool air blowing on them. I have had hard to understand readings from the gauges on AC charge only bottles.I really think that AC work is shop only espicallywhen you are talking about bleeding off into the atmosphere Post model, year mileage please

If the compressor is turning but the suction psi is not dropping then its a good chance the compressor valve plates are shot. Maybe time for a new A/C compressor, or a new car

The high side pressure really needs to be known but if the problem is a stuck expansion valve you could try a few firm taps with a hammer and see what happens if you can access the valve.

If the valve is stuck and refuses to cooperate then it will have to be replaced. This means the system will have to be discharged, the drier should be replaced, and the system will then have to be evacuated and recharged. This will be kind of iffy if you don’t have a gauge set and vacuum pump.

I’m always a bit antsy about A/C problems without knowing what is occurring on both sides of the compressor.

A friend of mine in the home AC business said to try adding freon anyway, but very slowly. What I did was tap on the both tubes as they go thru the firewall, using a socket extension and a couple of sharp raps with a hammer. No change, added a small amount of freon and the pressure increased slightly (70 psig), tried a couple more raps, still nothing, started to add more freon, then all of a sudden the sound changed, the pressure dropped and I was able to add a fair amount of freon until I got the pressure to the high side of full. It now works great, I can freeze my ass off if I want to.