Ac troubleshooting

[vza]

Hi all, 08 boxster. AC compressor does not come on. Seemed to have no psi when I went to add coolant. Added coolant to 25 psi but compressor remained off. Please advise how to troubleshoot. Keep in mind I'm doing this in cold weather.  Thanks v

[JFP in PA]

If you had no pressure in the system to start with, there has to be a leak somewhere that has vented the gas off.  At that point, just adding gas is not going to work; the system leak has to be found and repaired, then the system needs to be evacuated to a high vacuum level to get the air and moisture out before recharging with both gas and the correct system lubricant.

[vza]

Yes but don't I have to charge the system so I could charge it with with leak dye so I can find the leak. Then repair the leak evac system and add oil and coolant

[JFP in PA]

16 minutes ago, vza said:

Yes but don't I have to charge the system so I could charge it with with leak dye so I can find the leak. Then repair the leak evac system and add oil and coolant

 

You can pressurize it with dry nitrogen or argon with the dye for testing to limit the amount of freon leaking into the atmosphere, unless you have access to a freon recovery system, then you could use freon because you can limit the amount that escapes the system.  When we get a depressurized system in the shop, we do not use freon until we know we have found and fixed any leaks, and we have a freon recovery unit.

[vza]

I can't get the compressor to run and charge the system. Is it because of the low pressure switch. How do I charge if the compressor dosen't run? Thanks V

[JFP in PA]

10 hours ago, vza said:

I can't get the compressor to run and charge the system. Is it because of the low pressure switch. How do I charge if the compressor doesn't run? Thanks V

 

It probably is the low-pressure switch, which you can unplug and jumper temporarily to get the compressor to run. 

[vza]

Ok,unplug clip from low pres. switch and just jump the 2 terminals on the connector(wire side) assuming there are only 2. 

Edited December 30, 2022 by vza

[JFP in PA]

8 hours ago, vza said:

Ok,unplug clip from low pres. switch and just jump the 2 terminals on the connector(wire side) assuming there are only 2. 

 

Yes.

[vza]

Finally got back to my ac. Installed new condenser hose, expansion valve and receiver/dryer. 30oz of 134 and a little less than an oz of ac oil. It was 82 degrees my low read 45psi high was 230. Are these good readings? AC was approx 56 with the doors off( doin body work)

Edited July 2, 2023 by vza

[JFP in PA]

Nominal values for a correctly charged system @  82F ambient, measured at center vent:

 

Vent air temperature: 40-45 F

Low pressure side: 25 PSIG

High pressure side: 203-290 PSIG

 

I'd say you are a touch low on gas.

[vza]

Thanks for getting back John. I checked it again high was 225 which is in the  range from what you said. Low was 35 to 45 but the needle kept fluctuating back and forth back and forth keeps moving no pause. Is my low side too high? I was going to add a bit more but didnt get a chance. AC was blowing 58 on a 90 degree day 

Edited July 3, 2023 by vza

[JFP in PA]

Low side seems a tad high, but knowing gauge sets vary widely in accuracy, I wouldn't worry about it.

[vza]

Thanks