Shark Racer

I hooked a pressure guage up to the fitting right behind the compressor. (Blue Cap)

The thing ran 25 PSI on one cycle, and when it went to the higher cycle, the pressure shot up to about 45-50 PSI.

With the engine off, pressure was very high. >90PSI.

This is an R-134A system. What should my pressure be approximately and which way am I supposed to check it?

Thanks in advance...

-Steve

A C

The pressure of the refrigerent is directly related to it's temperature. Here is a p/t table for 134a
http://dodgeram.org/tech/repair/HVAC/R134a.htm

It appears that at 45-50 PSI the suction line temp would be about 40-45 degrees, which would be just fine. I am not sure about the lower pressure you got initially. When you shut the car off, the pressures in the system equalize. The 90 PSI you are reading is the static pressure when the system isn't running. When it starts, the suction side pressure drops, and the discharge pressure rises.


[Modified by A C, 8:57 PM 9/3/2003]

LAvetteman

How was the big line on the compressor? Was it sweating? Those pressures seem inline.

Shark Racer

I did not see it sweating.

The high pressure was in the "yellow zone" on the guage I was using, IE slightly high.

I had turned the A/C on in 95 degree weather and got little reaction. Cold air comes out, but not as cold as I think it should be.

45 psi is not too high for when it's cycling?

-Steve

zwede

The pressure is pretty normal. Maybe a little low. It will help getting the proper gauges that also measure high side.

On the low side I want to see the pressure going down slowly after the compressor kicks in. It should hover in the mid 20's for some time (a minute) and slowly decrease until it hits the cut-off which would be about 20 or so. A peak of 50 during the off-cycle is fine.

If the charge is low you will notice it short-cycling. Off/on every 15 seconds or so. Should be more like a minute.