I've recently opened up my system due to an engine swap. I've replaced a few o-rings, the low pressure schrader valve, the high side fitting, and had my system serviced at Sears. Supposedly they evacuated and recharged the system. My low pressure line that goes to the firewall is cold, but dryer/accumulator and high pressure lines are hot. Is the dryer supposed to be hot or cold? I'm just wondering if it needs to be replaced. The a/c compressor and cooling fans cycle on fine, but the system doesn't seem as cold as it should be. No visible leaks detected. I've also noticed that there is no visible water dripping underneath the car when the A/C is on (bad condensor maybe?) If someone can advise...

 

Well...after taking my car to a Chevy dealership for diagnostics, I've been told that my condensor o-rings and expansion valve o-rings are still leaking. My plan now is to replace all o-rings in the system that I can easily get to and hope this remedies the situation...
Perhaps I'll replace the accumulator just for good measure.

 

Seems I remember people saying the dryer should be replaced if the system was left open for any appreciable amount of time.

 

Accumulator/dryer should be cold. Like dripping water cold. Needs to be replaced when the system has been opened up, as there is a desiccant in it that will absorb atmospheric moisture when open.

Use Nylog on the o-rings. It helps create a good seal.