75 C3 that had ac but missing compressor . Bought a comp that I was told off a 75 C3 . Went to wire it and pretty sure the green on the comp connection goes to the pressure switch and the blk to gr . I cannot find a 75 correct wiring diagram so not positive where the other pressure sw wire is or where it goes/comes from ! If it is green as I seen on a 76 diagram I can’t find any green or any other wire that might go to the pressure sw ! Also on the AC hose end of compressor there is a smaller connection that I guess should have a black wire with a boot on it ? I can’t find that wire either ! My resistor is different that the 76 diagram n thats where the black with boot comes from ?? Anyway I’m not seeing any wiring left on the care for compressor etc ! I have a 75 wiring diagram but doesn’t have AC wires ! TY

Not the hose ends not correct

Note the resistor

Comp green to one side of press switch

 

The A/C has its own sub-harness to connect it up.
https://www.lectriclimited.com/produ...ng-harness-92/

It comes from behind the dash toward the passenger side (at least my '72 does). Look there for any existing wires from the original harness - but it may be easier and more reliable to buy the assembled harness than attempt to troubleshoot and fix what's there.

 

TY .Yeah I was looking for any loose wires but none ! I’ll get under it and look and maybe see if I can find under dash . Wiring diagrams I’ve seen ate no help !

 

I had the same issues on my '75 and used this diagram for a reference. Hope it helps!

 

Thanks . I do have a diagram but my problem is I can’t find the wires to the pressure switch and the blk with the boot ! Going to see if track them down today ! On the diagram there is the tan that goes on pressure sw and comes from Comp Sw also beside the Comp sw it shows a Master sw , can u tell me what/where those 2 switches are ?

 

I suspect the compressor and master switch are with the environment controls on the inside of the car. The diagram shows the tan pressure switch wire going through the dash to the interior of the car. You should be able to find the harness coming thru the firewall into the engine compartment and pick up the tan wire there.

I had the same problem with wire color codes not matching so I had wrote down the colors when working on the AC. If helpful, i am including below but reference at your own risk Harness

Yellow - resistor

Lt Blue - resistor

Grn - resistor

Dk Blue - relay high speed engage

Tan - to pressure switch - other side of switch feeds compressor and idle solenoid



Relay

Blk - Gnd

Drk Blue - High speed from switch

ORG - 12v fuse

Purple - Blower (Starter motor solenoid and starter interlock override relay)

(Pink goes to fusebox IGN)



Resistor

Yellow - Med1 speed on switch

Lt Blue - Low speed on switch

Grn - Med2 speed on switch

DK Blue - Out to Relay and Blower



Dash Switch (BRN Connector)

Brn - Pwr from fusebox

Lt Blue - Low speed med 1

Yel - med1 speed



Dash Switch (BLK Connector)

Tan - To pressure switch

GRN - Med2 speed on resistor

DK Blue -relay to enable high speed

 

Thanks ! I kind of assumed the tan went to the console selector wheels . It’s been pouring here in Pa all day and I had the car outside so didn’t do anything today . I will prob find the tan under the console or maybe behind the console where it heads toward dash etc ! Thanks a bunch for the wire colors !! I have a colored diagram but wasn’t sure on the 2 switches . Always good to have 2 heads on problem