A/C compressor, 99 cavalier, 2.4l?

tinkering w/a 99 cav., the a/c blew cold last week, now just hot air. i got a d-i-y

refill kit and plugged it on the low-pressure port. the gauge read 100 psi! it also said seek professional help (for the a/c, not me!, altho i probably need it) is it about to blow up? what could make it read so high since it recently worked fine?

does this sound like the compressor went bad? how do i tell what IS wrong with it?

i can pretty much work on anything, but sometimes i need a reference point to start from. any auto a/c people out there?


If the low side is at 100 PSIG just think what the high side must be. The advice offered about professional help is probably correct. Don’t even turn it on until you get someone who knows what they are doing to check it out. IF YOU have recharged the system repeatedly, it MAY not have needed more R-134a. Or an orifice may be plugged.

I have never recharged this a/c. was thinking maybe refrigerant was low, so got a d-i-y- kit. i am posting to this forum FOR info on maybe fixing it, anybody knows you can ALWAYS PAY someone to MAYBE fix anything. SURE, it would be nice if i was an expert in anything that could go wrong with a car, but then why would i be on this site? any (practical) troubleshooting advice is appreciated!

The engine, is she running when you take the pressure measurement? On an engine, which has been off for a while, the low side and the high side pressures become one (remember that thing called a “compressor”?).

You need this: http://www.sears.com/shc/s/p_10153_12605_00921026000P , and the Haynes TECHBOOK Automotive Heating & Air Conditioning #10425 manual. It’ll tell you stuff like: how to test the a/c; a/c oil, 9 oz.; a/c charge, 1.50 pounds of R134a; low side pressure, 32-65 psi; high side pressure, 150-324 psi.

When you service the a/c, particularly an older one, go for the lower figures, because an older a/c system has parts which have become weaker with age. These parts may, safely, withstand the lower pressures, but, may rupture if charged to the higher values (on the “high side”, or “low side”).

Some cars, say a Camaro, take a much lower charge (high side 115-200). So the pressure figures aren’t universal (not for all cars).

I found this photograph. Is this you, with Dorothy, on your way to find a …you know what? http://www.digicamhelp.com/photo_collection/mgm_new/pages/dorothy_strawman.htm
Sorry, I forgot to include said photograph. Maybe, I’ll go with you and Dorothy. Hold on, while I get my oil can for that other “fellow” who will be joining us, shortly.


It sounds to me like the compressor is not running. 100 Psi without the compressor running and refrigerant pressure equalized only tells me it was about 85-90F outside when you were tinkering with it. As others have suggested, step away from vehicle, and take it a shop that specializes in A/C auto repairs.

Working on the A/C system is not like working on most other systems on the car. For a total A/C novice, even with advice from experienced mechanics, A/C work is potentially dangerous to you and some potential mistakes you can make can seriously damage the A/C system. This is why you are getting advice to go to a professional. Don’t take it personally.

That said, others have already told you some of the basics on how to recharge but it’s not always simple. For example, you assume that since it is blowing warm you need a recharge. While that may be the case, a blend door could also be malfunctioning and a recharge might not even be necessary. There could be other reasons it is blowing warm too.

Consider getting a manual that gives you the high and low pressure values for the various ambient temperatures and an A/C manifold gauge set.