I recently put a new compressor and vacummed and refilled my system. I have a z3 swap in my Si. HR ac lines it worked fine for the first year until the compressor took a dump, now after two months with the new compressor well used off a type s, it was throwing cold air for 2 months then all of a sudden all of the coldness is gone. If I drive with the ac on itll get fresh but never cold I know its lacking some freon but my question is what would have caused it to need some more. IF I drive with the ac off this was when it was working fine when I were to turn it on alot of white smoke would come through the vents. any one have any idea why its not staying cold.

 

You may need to pull the evaporator out of the dashboard and check it out. The dash vents shouldn't blow anything out but air.

The evaporator is relatively easy to remove on these cars, but of course you have to replace the receiver/dryer again (one time use) once you re-open the system. If the evaporator is good, and it was just blowing dust through the vent system, you can replace the expansion valve and re-install everything. Then vacuum & fill and do a performance test. For a performance test, you just need to record the following info:

AC on full blast, upper dash vents only, set to recirculate with front doors open for 10 minutes idling:
- outside temp (check google)
- outside humidity (check google)
- center vent temp (use a pen thermometer)
- low-side pressure @ 1500rpm
- high-side pressure @ 1500rpm

Then we can fill out one of these test charts:

 

it wasnt dust coming out of the vents seemed like the freon it was like vapor and it was cold. I have not changed my dryer but didnt think I would need to since it was working but maybe I should do that. Im thinking of re charging and seeing what happens

 

Sounds like you should closely inspect the evaporator for breaks and leaks, and definitely replace the expansion valve (not that expensive, but very important). The expansion valve has 3 o-rings on it, so any one of those could have gone bad. But if the evaporator has any corrosion on it, replace it too (more expensive).

The receiver/dryer is supposed to be replaced every time because if the silica gel sack inside gets too much moisture in it, it will burst and spread throughout the system. The receiver is supposed to be replaced EVERY time the system is worked on. They are only $20 through autozone, and even less through amazon.

 

koo man thanks will do as said and see what happens!