AC retrofit?

I am attempting to install an A/C system in a '78 gray market SC. Can anyone tell me the layout of the wiring harness for this endeavor and would anyone have access to or know of a source for the original dealer installation instructions? Any light shed will be greatly appreciated.
Thanks,
Kurt

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Originally Posted by Kurt (guest)

I am attempting to install an A/C system in a '78 gray market SC. Can anyone tell me the layout of the wiring harness for this endeavor and would anyone have access to or know of a source for the original dealer installation instructions? Any light shed will be greatly appreciated.
Thanks,
Kurt

Welcome aboard Captain Kurt.

There is a very good basic schematic HERE
Also you can look at a Porsche PET catalog and get an idea as well.

In simple terms you need battery voltage to a primary AC relay. The circuit should be fused, 25-30 amps, between the battery and the relay. I'd suggest 14 or 12 gauge wire (overkill but worth it). You can safely estimate 15 amps for your evaporator blower motor, 7 amps for a front condenser blower motor, 5 amps for the clutch. If you use the largest diameter stranded wire as practical you will reduce your voltage drops on long runs, such as getting power to the clutch in the rear. You could, if you wish, use a second relay, as done in the factory system, for a front condenser blower motor (or 'other' condenser blower motor setups such as Kuehl Fender Condensers).
Though not employed in the factory system, you could install fuses for each load.

I doubt you will find 'dealer' nor 'factory' installation instructions for 78 onward. Early cars that had AC installed at the 'dock' or dealer were available and likely an independent repair shop that has survived since the 70's will have a set stuffed in an old file cabinet; a pattern for cutting the front condenser blower motor air pathway through the bottom of the trunk .... would be like having Willy Wonka Goldenan Ticket.

You can use an original factory a/c wire harness from any factory air car (salvage yard time), say 1978-1989. The harness connects the primary AC relay in the smugglers box with the thermostat switch and fan speed control switch and the fan speed control speed resistor pack.

Feel free to PM if you need navigation.

Griff

PS... Good Reading Material Here