A/C pressure in 03 vibe?

[thejas]

I was recently at a valvoline instant oil change and they checked my a/c pressure. It was well over 100 and in the red on their gauge. I had them check it twice and show it to me to make sure. My vehicle was off at the time so I don't know if that's normal or not. I really would rather not replace my compressor if I can avoid it. I was just wondering if this was a normal reading when the system wasn't even on at the time and most things I've read on here say it should be. Can anyone give me an idea on what needs to be on/off when I get a reading and also if it is high, what to do about it? I just thought releasing some of the pressure would work but I won't try it not knowing if it will hurt the car or not. Does anyone know what the normal reading pressure of the vibe is? Thanks in advance for all help.

[trb]

From this website: http://www.aircondition.com/tech/questions/82/

What static pressure should I expect to see when I hook up my gauge set.
Each refrigerant has it's own static pressure at every corresponding degree in temperature. The important thing to keep in mind is static pressure changes based on temperature. Any change of temperature brings with it a change of pressure. The greater the temperature, the greater the pressure. You can use a refrigerant pressure chart to find static pressures at various temperatures. Static pressure will not be used to determine if a system is fully charged. Using the chart below, if the R-134a system has a static pressure of 88 psi at 80 degrees F., we can then assume the system has some amount of liquid refrigerant. The system may be full -or - may not be. At the same temperature, if the system showed only 75 psi, we could say with confidence, the system is low. This is because static pressures shown on a temperature chart would show inadequate pressure for the presence of any liquid refrigerant.

To me that place sounds like they may be just fishing for work. Did you have them look at the system? Are you having any problems with the AC? Did they hook up true manifold gauges or just a single gauge? True pressures should be measured while the system is running, and you should see a low pressure on the low side, like 30-50 or so, and higher on the high side, 150-200 or so. I would take it someplace else and have it checked if you are concerned about it.

[thejas]

From this website: http://www.aircondition.com/tech/questions/82/

What static pressure should I expect to see when I hook up my gauge set.
Each refrigerant has it's own static pressure at every corresponding degree in temperature. The important thing to keep in mind is static pressure changes based on temperature. Any change of temperature brings with it a change of pressure. The greater the temperature, the greater the pressure. You can use a refrigerant pressure chart to find static pressures at various temperatures. Static pressure will not be used to determine if a system is fully charged. Using the chart below, if the R-134a system has a static pressure of 88 psi at 80 degrees F., we can then assume the system has some amount of liquid refrigerant. The system may be full -or - may not be. At the same temperature, if the system showed only 75 psi, we could say with confidence, the system is low. This is because static pressures shown on a temperature chart would show inadequate pressure for the presence of any liquid refrigerant.

To me that place sounds like they may be just fishing for work. Did you have them look at the system? Are you having any problems with the AC? Did they hook up true manifold gauges or just a single gauge? True pressures should be measured while the system is running, and you should see a low pressure on the low side, like 30-50 or so, and higher on the high side, 150-200 or so. I would take it someplace else and have it checked if you are concerned about it.

I thought the place was a little shady to begin with so no, I did not have them look at the system. I have no issues with the ac. It looked to me to be a single gauge on the passenger side of the car but the hood was up so I couldn't see much, or specifically where, it was. I was thinking of checking and repairing myself. I've done the intake manifold gasket, alternator, cleaned the throttle body, maf sensor, rotors, and pads, so I feel very comfortable working around a car. Is there a way I can make checks and determine what to do from there. If so, please link me to a how to for this stuff. Thanks for such a quick repsonse. I appreciate it!

[trb]

I would not worry about it unless it stopped cooling or is not cooling enough. But if you want to make sure, do you have an Autozone by you or other parts chain? I know AZ will rent out the AC manifold gauge kit for a deposit you get back when you return it. You just hook the gauges up to the high and low pressure sides and check the pressures when the AC and engine are running. The link I posted gives you some info on how to use the gauges to see if anything is wrong with the system. But frankly, if it is cooling just fine, there should not be a problem. Usually a system starts leaking and loosing pressure and then does not cool. Most AC problems are related to leaks that can lead to other problems, but otherwise, it is a sealed system.

That shop sounds like a good place to send a TV undercover news investigator!