I recently replaced my AC compressor, drier, and low pressure line. When we recharged it, it was at about 50psi on the low side...

It never really blew COLD air, but cool air when it wasn't too hot out. I decided to see what the low pressure side was at, and it's at 120psi now. I got in the car to shut it off and now it's blowing hot air.

Can anyone clue me in on what to do here?

 

Sounds like it's overcharged, or there's a restriction somewhere. My helms says 86-95* ambient, high humidity low side should be 42-46 PSI for my car. Yours shouldn't be that much different.

 

OK hooked up some real gauges. Both the high and the low are 145-150psi, so that means my compressor is bad, right?

 

Did you do anything to the expansion valve? Could be a bad compressor more that likely though. Does the clutch engage on the compressor at all?

 

Yeah it engages...I didn't touch the expansion valve. I should have replaced it.

 

Is it possible that the compressor is still good but the expansion valve is bad?

 

The compressor is working?

A condtion that shows a HIGH LOW SIDE and a NORMAL HIGH SIDE can be a defective thermostatic or pressure switch, which ever your system has.

How does the compressor run does it cut out rapidly?

Have you done the touch test? What gets cold and what is hot? Is there any frost forming on the lines?

 

A large amount of air in the system causes a high low side and high high side.

I just realized you didn't mention pulling a vacum on the system after you replaced parts. Did you use a vacum pump to get all the air out?

Very possible

The expansion valve could be stuck open or the temperature-sensing bulb inoperative; when you have a high low side and a normal to high high side. If this was the case the Evaporator would blow out warm air and have heavy sweating/the suction line would also have heavy sweating.

 

Is the liquid line really hot? If so it's probably overcharged or a condensor malfunction.

 

The compressor cycles on and off frequently...

We vacuumed the system for an hour before recharging, and it held vacuum fine as far as I know. There is no frost/condensation on any of the lines I don't think.

 

What was the initial reason for replacing the parts you mentioned? A/C wasn't working? Or this same type of problem?

 

You are sure both sides are at 145psi?? Was the A/c running when you checked it?

For a high side reading for a 134A A/C you should be near 215 to 240 and be on the higher end if it is a humid day.

Sorry I can't be of much help.

 

Well if your compressor clutch is kicked in and you have equal pressure on both high and low sounds like the expansion valve is stuck replace it.You should be 30-45 on the low and i dont like to go any higher than 200 on the high but it varies a little bit on different pieces of equipment or automobiles

 

My Pacesetter LT's are really close to the AC line (I had to bend the line). When I dropped my tranny, the motor lowered down and the header broke the AC line in half....so when I replaced the line, I replaced the compressor too as preventive maintenance, along with the drier.

 

ttt