On my 1990 chevy truck the A/C compressor clutch wasn't engaging so I added some 134a (the cooling system has been retrofitted). It started working but now every time I start the truck with the A/C turned on, the belt kicks off of the pulley immediately. The engine runs fine with the A/C off. I think my compressor is just worn out, can someone confirm this? Also both refrigerant ports hiss and leak coolant when the caps are off but the caps seem to seal them. This isn't normal is it? I think I may need to buy another retrofit kit.