I have a 1970 SS 454 Monte Carlo with air conditioning. It is all original and the a/c did work. The compressor started to make noise and since it is very old ,possibly the original I will be changing it. NOW for the problem. On this vintage GM the control panel when switched to Defrost, A/C or possibly Bi level the compressor is supposed to have power. It does. Where the problem comes in ,is that the power wire ( plugged or unplugged) for the compressor also started to come on in the heat zone as well. It will shut off in the OFF position , however I am quite certain the compressor wire is not supposed to have power in the HEAT position. I have started to work in the dash area , but I have not started to chase this problem yet. I thought I would ask the experts first. I am thinking there might be a relay stuck on , possibly when the compressor went bad ? Your thoughts and advise please . Thank you in advance.