why does my a.c freeze

like tht title says...it freezes at lights but cruising down the road its fine...

If you are SURE the evaporator is freezing than the charge is low.

I would check the charge, it could be that the system is overcharged. With the way that camaros are set up without the high/low pressure switches it is really easy to do. Did you recently fill the system?

I would check the charge, it could be that the system is overcharged. With the way that camaros are set up without the high/low pressure switches it is really easy to do. Did you recently fill the system?

usually, an overcharge will be warm, a low charge will freeze the core

yes...it was just not working...i had it vac for 30 minutes and recharged...now it freezes up at lights...

Thats what i thought also until i went to charge my system we couldnt find the high and low pressure switches so i consulted a local AC shop and he explained to me how the AC system in the camaros was different. It uses a Thermal Expansion Valve instead of high/low pressure switches. The way he explained it, and i am no ac expert, but he said in this system if it was overcharged it would start freezing up. We were dropping off some work trucks to be serviced so i asked hime about charging the F-bodies. he said you couldnt really go by line pressure and from a complete vacuum you just add about 2 to 2.5 lbs and see how it works. if it freezes let some freon out.

Normally a low charge freezes the evaporator, and high pressure would shut off the compressor by the pressure switch. But you had it evacuated and recharged so maybe the evap coil is dirty or the thermostatic expansion valve is faulty. The evap temp sensor should cycle on & off the compressor to keep it from freezing up also?
At least your compressor is working, thats the expensive part of the system!

dammit these big words are confusing...i just want a few ideas so when i go to a mechanic he dont give me the run around...i can build a damn motor but i dont understand a friggin ac system...lol

Quick easy answer, As long as nothing needs replaced you either need to add freon or remove freon. When the AC guy puts a decent set of gauges on the system he should be able to tell.

mine is freezing on the hwy and working at lights and in traffic.. my gauges read 45/250.. I had hte system apart to replace the ac lines, dryer, and expansion valve.. put two cans in it.. had this problem.. figured it was low.. so added a 3rd can.. and still have the problem.

If its freezing at lights its OVERCHARGED...undercharged would make it blow warm air.

Stephens: Check the yellow sticker on the blower motor case to see how many lbs of R-134a its supposed to take,you make have put have a can too much in it,or the orphis (sp?) tube maybe clogged.

My car doesn't have an orifice tube it has an expansion valve. I really don't think it is overcharged because.. it was doing this with only two cans in it.. I think I've always bput 2.5 cans in.

So.. I checked the "low pressure port" with my gauges and it was really high.. so I thought.. maybe instead of it freezing.. the expansion valve was jacked up... ( I replaced this last week) So I went and exchanged it for a new one. I evacuated the system and charged it.. The system cools great.. but I have to jump the compressor. I reset the PCM like I've done in the past.. but the computer still wont turn the compressor on... How much pressure is too much? it has around 50-90... when the compressor isn't on, if I turn the compressor on it sucks it down to 45-90.

get a scanner and check what the PCM sees for A/C pressure, if thesensor has failed, the A/C wont work

ok.. so I put the gauges on today.. and intermittingly.. the high pressure port will climb all the way up to 450lbs (at least that's the max my gaugues go.. so I shut it off right away.. Then some times it runs normal.. 50lbs/250lbs so there has go to be some moving part.. some kind of valve that is screwing up.. I've replaced the expansion vavle twice.. what else is there?

when the high goes high, what does the low do?

The times when the system is working normal.. my normal I mean I still have to jumper the compressor but the pressures are around normal. When I rev the car the low pressures goes down and the high pressure goes up. BUT.. when the HIGH pressure is over pressurized.. the low pressure sided does not move.. the high pressure just taps out..

So I FINALLY have the A/C fixed. The reason the AC was over pressurizing was because the fans were not coming on when I was jumping the compressor. So.. if any of you ever jump the compressor to get the car to accept freon make sure and jump the pressure sensor to make the fans come on high. I figured out that the pressure sensor was bad when I hooked it up to a scanner and saw that it said "pressure 0 psi" and "ac clutch disabled" so.. $54 later.. ( list price of pressure sensor) things are working great.. Thanks for the help everyone..