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Old 06-08-2020, 06:19 PM   #92
swissarmychainsaw
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Join Date: Jun 2009
Location: san francisco, ca (east bay)
Posts: 674
Re: Suburban A/C fix + Vintage Air?

Quote:
Originally Posted by hatzie View Post
Looks like you have a compressor cycling thermal cutoff switch with a capillary tube in the Evaporator. There should be a Low pressure cutoff switch on the accumulator as well. The aftermarket compressor and or hoses likely has provision for a high pressure cutout switch. If you're running R134a you'll want to add a HPCO switch in series with the LPCO and thermal switches because it has a tendency to run much higher pressures than R12 or HC blends.
I'd use a relay to offload the control amperage to the actual compressor clutch so the high amp load of engaging the electromagnet is run through an easy to replace $1.25 relay rather than the HVAC controls and the LPCO and Thermal switches.

Get a relay socket rather than using 1/4" disconnects. It makes the wiring job look better and it's much easier to replace the relay when and if it needs to be done.
Run a ground in series through the LPCO, HPCO, and Thermal switch to terminal 85 of a Mini ISO Bosch Automotive relay.
Run the Green AC compressor "on" wire from the HVAC control panel to terminal 86 of the same relay.
Run a 14ga wire through a 16ga fusible link or a 20A ATC fuse from the J stud on the firewall to the relay common terminal 30.
Run a 14ga wire from relay terminal 87 (normally open) to the actual compressor clutch plug.
I'm trying to get the wiring sorted out for the trinary switch and Vintage Air only used two colors of wires.
Does this look right?



Upper left Black wire: This is the Original ON green wire that passes through the Low Pressure switch. This wire originally would have plugged directly to the compressor.

Upper right blue wire: To terminal 86 (trigger) of the Fan relay.

Lower left blue: Keyed power.

Lower right black: to 86 (trigger) of Compressor relay.

Thanks for the help on this!
I have a new LPCO on order, I'm getting close!
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