A/c low refrigerant

[JayAllah]

I have a 1994 Cadillac sedan deville, 4.9 motor. I recently had a vacuum leak fixed so that my air would go thru vents. I serviced the compressor myself with a refill kit, and followed directions to a tee. I used 3 cans @ 12 oz and it only held at 40 psi. I could have added another can to makebit 45 to 50 psi, but figured it wouldn't make a difference. Drove around with system blowing on full blast for 30 mins and all of a sudden my onboard diagnostic reads " ac compressor off" and " low refrigerant"

Could anyone tell me what could possible be the problem before I take it to a professional

[winterset]

I have a 1994 Cadillac sedan deville, 4.9 motor. I recently had a vacuum leak fixed so that my air would go thru vents. I serviced the compressor myself with a refill kit, and followed directions to a tee. I used 3 cans @ 12 oz and it only held at 40 psi. I could have added another can to makebit 45 to 50 psi, but figured it wouldn't make a difference. Drove around with system blowing on full blast for 30 mins and all of a sudden my onboard diagnostic reads " ac compressor off" and " low refrigerant"

Could anyone tell me what could possible be the problem before I take it to a professional

It should only be filled to 35, so it's a good thing you didn't take it to 50!! can you see oil dripping out of the system from anywhere? put your pressure gauge on it again & see what you have. If it's still at about 40, then it can be a bad sensor. I suspect you lost it all because of a bad seal in the compressor.

BTW a professional + a 16 year old AC = $$

KHE is our AC expert.

[KHE]

Inspect the entire system - all lines, condenser, compressor, accumulator, etc. for oil or greasy dirt as evidence of a leak. It sounds like there is a large leak in the system somewhere.

A low side only gage is really useless. An A/C system is not a tire... it requires a specific quantity of refrigerant to function properly. You must use a vacuum pump to draw a vacuum on the system and then cherge the refrigerant into the vacuum or you will have air in the system which will raise system pressures considerably and reduce cooling performance.

[JayAllah]

I checked everything and the only thing I saw leaking was the area around low pressure connection. It's a bluck sut. I also have lost psi as well

[KHE]

That is probably the source of the leak. What is the conditon of the o-ring in the plastic cap? The schrader valve coule be leaking and in need of replacement.