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after running a 12 volt source (not sure why it was missing in action)
I was able to jump the relay to kick the compressor in, and charge the system with refrigerant. system is putting
out cold air thru the bottom vents...will not switch to the top vents.
I cannot get the system to switch on the compressor by itself with the control wheel in the car.
have tried jumping across the low pressure switch with no effect.
any ideas?
thank you,
Gary
and i suggest you get gauges (can get for free rental if 134 stems..) and see where you are at. Is it R12? was it vacuumed? details of history helpful.
then see where you are
mine is a 75....still with the old style controls....
its R134.... she is charged and if the compressor is jumped to get started, she is putting
out cold air. just not sure why the controls will not start the compressor.....starts the fan fine, just not the compressor.
Looking at the 75 line diagram it is the same as the 74 link below.
25 AMP Fuse circuit #50 Brown wire powers the Master SW.
Once Master Switch closes Circuit #962 Lt.GRN wire sends power to the COMP SW
Once Comp SW closes power is now at Circuit #963 TAN wire of the Pressure SW
If Pressure SW is satisfied Compressor clutch should engage via Circuit #59 Dk.GRN wire. http://repairs.willcoxcorvette.com/w...-schematic.png
sounds like a wire in the circuit between the switch and the compressor. i think that low pressure switch on the high pressure side is the only electrical gizmo in between. look for 12 volts at the low psi switch. still using the orig VIR? cuz if VIR eliminator is installed there is another pressure switch in the system.
does anyone with a air condition 75 have a picture of where the 12volt fused power comes over the the ac relay on the passenger side?
I had half of a fuseholder on the ac relay side, but no 12 volt power coming to it... I'd like to see how the factory supplied that power please.
I currently put in a power line from the output on the alternator but would like to do it correctly.
ok. the big AC box on the firewall. look just outboard of it and down. you see this? or this? the top one is the original VIR. as in VIR eliminator. the second is the accumulator that is part of what replaces that overly complex and really pricey Valve In Reciever. and the accumulator will have a pressure switch on one of the schrader taps on it. the VIR setup will run with R134. but it is close to the last choice for AC systems in a car.
Last edited by derekderek; Jul 6, 2022 at 03:45 PM.
75 a/c compressor not kicking in
