Disassemble the system, take the hoses off, throw away the dryer (buy a new one) flush out the condensor, compressor, evapourator and lines using a proper AC system flush solution. Replace any incompatile O rings and hoses. Reassemble and fill with R-134a.I agree with Brad's cousin. I have converted both my '71 and my '70 Imperials to use R-134a with excellent results.