Air Con moisture(?) - 1995 Corolla

Hi,

This 20YO car has never had an AC gas top up or service. Last summer my air con would blow vaguely cold for a minute and then blow warm. I figured it was low on gas so this summer I topped it up with 134a. Most of a can went in and it has held that pressure for a few weeks now. Problem is that it will blow cold for a few minutes and then blow warm. Somewhere I read that there can be moisture in the system which freezes in the expansion....valve is it called?

So I was going to try to replace the receiver dryer. My question is, do I really need to go to the prohibitive expense of buying or paying someone to vacuum out the system to boil the moisture off? Surely most of the moisture will come out with the gas when I empty the system, and the tiny amount of moisture that is in the air that will then fill the lines would more than easily be absorbed by [a small fraction] of the dessicant in the new receiver dryer, wouldn't it?

thanks,
p

you may be right, if there's no leak anywhere, you may want to consider to discharge it and charge it back and check for leak again.

im thinking, check your compressor, does it work? about your fan/s?

Thanks Ashton,

It actually has lost a little pressure over about a month or so and I'm about to pus some refrigerant system sealant in there. I'll post how it goes....