Air Conditioning problem
1979 GMC Sierra V8 Two Wheel Drive Automatic 120000 miles
1 year ago I replaced the A/C compressor, Receiver Drier and flushed the entire system (disassembled system including hoses. Converted system to R-134 and stayed cool all summer last year. This past summer had to reservice the system with 134 and discovered that the cycling switch was defective. I replaced the cycling switch with an after market switch (Auto Zone) marked for 134. After installing the 134 switch the system worked for approx. 5 minutes and blew the system fuse. I have replaced several fuses and they continue to blow. Should I have replaced the switch with an R-12 switch? The system worked fine for more than a year with the original R-12 switch installed. Is the R-134 switch set at a different pressure than the R-12 switch?