New owner with part time A/C problem

hi:
i'm a new 1991 gvr4 owner #933/2000 my problem is that the air conditioner works intermitently, it's only work when the car is fully warm and only for a short time then the compressor stop working.

please, any info on this.

 

take it out. you'll lose some weight, and gain some power.

 

[ken inn]

expansion valve.

 

ken inn:
what and where is the expansion valve?

thanks

 

The expansion valve is located inside the dash with the evaporator. First and foremost, make sure the a/c has a full charge of R12. If it has been converted to R134a, they probably didn't change the valve. Also, moisture (water) in the a/c system can cause this. Reason: when freon goes thru the expansion valve it goes from a liquid to a gas. Like nitrous, it gets cold doing that. If there is moisture in the system, the expansion valve builds ice up to the point that it freezes closed. Obviously, it stops the flow of freon. Once the heater core warms the expansion valve up thru radiated heat thru the housing, the valve reopens and passes freon till it freezes up again. So you have two options, or three. Have the system evacuated and purged and refilled. Make damned sure there is an accurate scale inside the evacuation system. newer models have a scale. with freon at 100 bux plus a pound for R12, they will say it isn't useable, which is bullshit, because the evacuator recycles it. 2, you could have it evacuated, replace the expansion valve as a precaution and have it charged, or 3, have it converted to r134a, have the expansion valve replace with the proper R134a valve, and then go buy your freon at the parts store if it ever needs topping off and do it yourself.
If the system has a sight glass on one of the lines, look for bubbles flowing past the sight glass while the system is working. that means air is in the system. If you don't see anything flowing, the expansion valve is frozen or the system is way low on freon. My experience only, but I doubt anyone will diss me on my diagnosis.
dave

 

thanks Dave, your diagnosis make sens to me so i will give it a chance

 

[ken inn]

i did the conversion last year. if your system is still holding pressure, all you need to do is get a kit(pep boys, 45 bucks), evacuate the r12, put on the new hi and low side fittings, and charge er up. the kit will contain everything, new fittings, charge hose, oil charge, and r134. but, i still think you need an expansion valve, and you gotta open the system to change it. just to be safe, i would then suck it down and throw a drier on it.

 

[turboflanagan]

The low pressure switch keeps the compressor off below 30deg F. If your system is low on freon, it may have just enough in it to reach this pressure when the under hood temps get high. Then your compressor comes on once or twice and the pressure is again too low and won't come on again.

Best way to start is to see if you have a full charge of freon. Know anybody that has a set of gauges to put on it?

I use a r12-like-product called Freeze-12 that does just about as well as r12 and saves the hassle of converting. Just add it straight to r12 to top the system off, but the best thing to do would be find the leaks, fix them, put a vacuum on the system for about an hour, add some a/c dye, and recharge with freeze 12 or whatever.
Freeze12 is about the same price as r134a too.

 

Where can you buy freeze 12? Never heard of it. My system is still r12 and holding, but I only have one can of r12 left out of the 4 cases I bought before it became a bad thing. (lots of cars charged though) Do they use the same style of top or do they use the 134a screw type? I know lotsa questions... Just never heard of anything that WASN'T propane or something just as flammable being available. We have Oreilly's, Champion, Autozone, Carquest, Pep Boys, and a few others around town.

Thanks
dave

 

meeh!

my A/C is still fried...i know the controller box behind the glove box keeps shorting, but I don't know why.

Any inputs???

 

[turboflanagan]

I don't think that the national stores around here have had it, but I got it at a local mom&pop type parts place. We use it at work if working on r12 vehicles.

I also don't remember if it has the small screw-type top (I think it does), my adapter just punches a hole in the side of the can.