a/c clutch will not engage

[El Supracabras]

No you will only see oil in there if the compressor is pumping. Retro fit kits are usually wherever the R134A is kept. Ask the counter person if you cant find them. You will also want to change the receiver/dryer (canister w/ window). There are 2 switches in the pipe going into the firewall just under the passenger side strut tower. I don't remember which is which but one controls the fan and the other is called a dual pressure switch (hi/lo), this one would cut out the compressor clutch if triggered by an incorrect pressure or if it was defective. Good luck.