AC questions

[lowriderdog37]

OK, I've been researching this for a while, but don't know what to do with the current pricing. I am working on my 85 300cd. My AC works just a hair less then it did last year, however I have noticed it does something weird. I don't get any AC when it's raining. Any ideas on that? I don't know if there is a leak, but I haven't seen any dye stains anywhere (if that matters).

I want to do at least a semi-rebuild of the system, being price conscious. I don't really want to drop the $250 for a new compressor, but I plan on replacing the seals, dryer, and evaporator. I know most people here like to stick with the r12, and I would really prefer to do that. The biggest problem is that the best price I could find on r12 is $23/ea from a member here. I can go to any store and get r134a for like $4, and freeze-12 for just a little bit more.

The model number on the current compressor is 1131627, it doesn't say anything about r4. I don't know if it's the original, but the sticker says it contains r12, and the valves are still r12.

I don't know much of anything about AC other than what I have been reading lately, so any advice is appreciated.