a/c problems
Thread Starter
Teching In
Joined: Jun 2007
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a/c problems alrighty, I have a 99 trans am that will not hold any freon it seems.... everything was good untill just a few weeks ago when I was driving and all of a sudden no cold air anymore.. I went to autozone and bought some more freon and a gauge and everything was fine for about 3 weeks. now the same thing no more cold ac. so I got another can and hooked up my guage but the guage says that it is filled. so i am leary of putting anymore in while iit says its filled so I went ahead and added it and then added a a dye that would detect a leak. so far nothin that I can see has come out and that was 2 weeks ago and Im still having the problem lost ac again. please advise
Thanks
Chris
Thanks
Chris
TECH Senior Member
Joined: Dec 2001
Posts: 5,399
Likes: 3
From: Jacksonville, FL
What is the static pressure with the car off? Should be around 100 psi. Usual places to look for a leak are at the compressor, where the high side line connects to the condensor, or the lines along the passenger side going towards the evaporator.
Take it to a shop. At $6 a can you're thowing money out the window. Pretty soon what you have in wasted refrigerant would have been enough for a tech to find the leak. In fact for what you wasted already you could have paid for a leak check.
Just remember, when your freon charge is low it has a leak, more freon is going to leak right back out so don't bother putting more in it.
Never heard of a static pressure check, I know what it is but it's useless, at 86 degrees 134a is at 97 psi, at 100 degrees it's 124 psi. You cannot leak check or determine proper charge like this.
You could have a leak check done, then when the leak is found you might be able to do the mechanical work, but do you have a manifold gauge set with high and low gauges? Vacuum pump?
The synthetic oil in the system absorbs moisture in the air quickly, so when the system is open you need to do the repair quickly and evacuate it after all parts are replaced.
So many times a cars a/c system gets worked on and never cools as well as it used to, thats because moisture in the oil creates a film that coats the inside of the evaporator and condenser, this reduces heat transfer.
I run into this all the time with home systems that use the same synthetic oil and have been worked on. They cool well in moderate temperature, but when it's real hot out it cannot "keep up". Same theory applies to cars. Thats why you might hear several people say they did this or that and it works like new, but on the hottest days it really doesn't cool well, a lot of people blindly assume it's leaking again and add more freon. It's a circle a lot of people run around in and most eventually end up with the car in a shop, hopefully the shop will start from scratch, find the leak, flush the system (most important), replace parts, evacuate and charge.
Just remember, when your freon charge is low it has a leak, more freon is going to leak right back out so don't bother putting more in it.
Never heard of a static pressure check, I know what it is but it's useless, at 86 degrees 134a is at 97 psi, at 100 degrees it's 124 psi. You cannot leak check or determine proper charge like this.
You could have a leak check done, then when the leak is found you might be able to do the mechanical work, but do you have a manifold gauge set with high and low gauges? Vacuum pump?
The synthetic oil in the system absorbs moisture in the air quickly, so when the system is open you need to do the repair quickly and evacuate it after all parts are replaced.
So many times a cars a/c system gets worked on and never cools as well as it used to, thats because moisture in the oil creates a film that coats the inside of the evaporator and condenser, this reduces heat transfer.
I run into this all the time with home systems that use the same synthetic oil and have been worked on. They cool well in moderate temperature, but when it's real hot out it cannot "keep up". Same theory applies to cars. Thats why you might hear several people say they did this or that and it works like new, but on the hottest days it really doesn't cool well, a lot of people blindly assume it's leaking again and add more freon. It's a circle a lot of people run around in and most eventually end up with the car in a shop, hopefully the shop will start from scratch, find the leak, flush the system (most important), replace parts, evacuate and charge.
TECH Senior Member
Joined: Dec 2001
Posts: 5,399
Likes: 3
From: Jacksonville, FL
The reason I asked what his static pressure was is to determine if there was any refrigerant at all in the car, since it sounds like a leak issue - and yes, the pressure will be different depending on the ambient temp - that's why I said "around 100 psi." Before even trying to charge the service manual says to read the static pressure. Didn't mean to imply that means it's full, just enough to start checking the charge, soon as the compressor starts low side will drop and high side will increase.
Originally Posted by 2001NBMZ28
The reason I asked what his static pressure was is to determine if there was any refrigerant at all in the car, since it sounds like a leak issue - and yes, the pressure will be different depending on the ambient temp - that's why I said "around 100 psi." Before even trying to charge the service manual says to read the static pressure. Didn't mean to imply that means it's full, just enough to start checking the charge, soon as the compressor starts low side will drop and high side will increase.
You and I might know this but he may not so I just said to not use this as a leak checking procedure.
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Thread Starter
Teching In
Joined: Jun 2007
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thanks for the help guys. I know alot about the cars mechanics and electrical, but dont know jack about ac or any of its components. I will take it over to a shop that does A/C and see if I can get it straightened out by them... may be late in the season now but Id rather just be able to click it on and have it working when it gets hot out next year then have to take it to a shop at the beginning of summer. Thanks guys
Chris
Chris
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Originally Posted by Abe99
I think auto parts stores sell a dye you can put in it to determine where the leak is. that might cheaper than taking it to a mechanic.
PUT THE DYE IN IT, FIND THE LEAK. THEN WHAT? THEN TAKE IT TO A MECHANIC WHO HAS THE PROPER TOOLS TO FIX IT.
JUST TAKE IT TO A SHOP. THEY SHOULD TAKE THE DIY **** FOR AUTOMOTIVE A/C OUT OF THE PARTS STORES.