Mechanics

AIR CONDITION STOPS WORKING AFTER RUN

1995 Pontiac Trans Am

Air Conditioning problem
1995 Pontiac Trans Am V8 Two Wheel Drive Automatic 143000 miles

I have a 95 pontiac trans am. The AC works for about 10 mins when I start the car up in the mornings. But once the car has warmed up the AC will stop blowing cold. I've checked and it has enough freon. When the AC is blowing cold and I stick the pressure guage on it reads normal. But once the AC stops blowing cold and I put the pressure guage on it the pressure guage reads maed out. What could be causing this? Do I need a new AC compressor?
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Josh95Transam
February 22, 2010.




Hello Josh95Transam

An A/C system that blows cold air for awhile then warm air is probably freezing up. This can be caused by air and moisture in the system that allows ice to form and block the orifice tube.
Evacuating the system with a vacuum pump will purge it of unwanted air and moisture. Evacuation should be done with a vacuum pump that is capable of achieving and holding a high vacuum (29 inches) for at least 30 to 45 minutes.
For best performance, an A/C system should contain less than 2% air by weight. For every 1% increase in the amount of air that displaces refrigerant in the system, there will be a corresponding drop of about one degree in cooling performance. More than 6% air can cause a very noticeable drop in cooling performance, and possibly cause evaporator freeze-up.

Tiny
Mathiaso
Feb 22, 2010.
I don't think that's the problem because I can start up the car leave the AC complete off and then turn the AC on 20 mins later and all I get is hot air and the guage reads that I have to much pressure once the AC starts blowing warm air.

Tiny
Josh95Transam
Feb 22, 2010.
I do not understand this" But once the AC stops blowing cold and I put the pressure guage on it the pressure guage reads maed out". What do you mean by

''pressure gauge reads maed out?&Quot;

Tiny
Mathiaso
Feb 22, 2010.
Maxed out. Like there's way to much pressure in the line.

But evermind disregard my second post because I let the TA run for 40 mins with the AC off and then turned it on and it blew cold. But then let it run with the AC on and it stopped blowing cold air after about 20 mins. So your right it's freezing up.

It would be the evaporator valve that is freezing up right and isn't that under the passenger side dash?

I just wanted to take a look at it to see if I did see that it was frozen because I remember having my AC unit in my apartment freezing up some times and you could open it up and see everything frozen.

Tiny
Josh95Transam
Feb 23, 2010.
Hello Josh95Transam

Too much pressure explains also that the system is freezing up, probably the evaporator and it may be caused by moisture in the system.
Replacing the evaporator will not solve the problem because a special vacuum pump must be used to get moisture out of the system anytime the air conditioning system is opened also the federal clean air act prohibit opening the air conditioning without proper equipments and there is a fine and money to the whistle blower.
What you need to is to take your car to a shop and let them clean clean and evacuate the system and you can take it home and charge it yourself.
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Tiny
Mathiaso
Feb 23, 2010.
I wasn't planning on replacing the evaporator I was just wondering if that's the part that freezes up. I'm taking it to the mecahnics this weekend. I'm just going to let them do the whole thing. I'll let them clean and evacuate the system and also let them recharge it. I'm pretty good with cars but when it comes to AC units I don't know jack about it. Thanks for all your help.

Now I just need to make another post and figure out what's wrong with my truck. I think the computers gone out in it.

I just almost want to go back to my 68 mustang that had no electronics accept a MSD box and a stero. They're alot easier to work on. Lol

Tiny
Josh95Transam
Feb 23, 2010.
Hello Josh95Transam

Thank you for your donation and for visiting 2CarPros. Com we hope to help you again the next time you need us

Tiny
Mathiaso
Feb 23, 2010.

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