Guys, i'm still confuse about the ac on my 1978 280z, My 280z seems to have 2 switches, one is on the drier and the second is on the line that connects to the drier. Is one of the switches the low pressure and the other the high pressure switch? TTACH] Heres some pictures. Thanks

That is weird indeed! I have never seen a dual setup like that. Here is the deal, assuming the AC system is charged and the Compressor will engage when the unit is turned on, then you could try to unplug the switch on the Drier first and see if the compressor continues to function. Next do they same thing with the other switch on the hard-line and see what happens. Look at the compressor clutch. Is it engaging when one of the switches is disconnected? Does the AC cycle on and off?

What I think happened is in the past, someone added the hard-line with a fitting as a repair. The original drier did not have the pressure switch port in that configuration either. If I am not mistaken, the Z only had a pressure switch on the drier. The ZX had the pressure switch on the hard-line, so it's presence baffles me. These switches may be wired in parallel which would make one or the other redundant.

Once your detective work is done, you should only leave one functional. Detach the other or plug it.

there are aftermarket switches that are both high and low cut out.

i'de install a dryer that doesn't have a pressure switch fitting and just

have the 1 switch.