broken/worn ac compressor washer
The compressor has two washers between the pulley and the compressor.
To fix the issue, all you have to do is remove the AC pulley and toss one of the washers in the trash and replace it with a new one.
compressor clutch not engaging properly
The AC compressor clutch may be becoming becomes less efficient with age and it does not engage properly. The result of this is no cold air coming out.
Click HERE to see what steps you can take to troubleshoot it and then fix it.
bad soldering connection on temperature change knob
In a lot of rx8's, the soldering on the temperature change knob is extremely faulty from the factory which causes no connection between the board and the knob itself.
To fix it, pull out your radio, disassemble the radio until you get to the bottom part where you can slide out the AC controller unit (with the board) and just solder 3 of the connections on the temperature control knob in the back.