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A/C pressure switch differences


Well-Known Member
Feb 18, 2013
Country Flag
Early on this year, i retrofitted a full a/c system from a 1991 import HDJ80 to a UK spec 1994 HDJ80. I found the whole wiring loom complete, and the retrofit wasnt particularly hard to do, as i had the dash out anyway to replace a leaking heater core.

Unfortunately, i pulled the system from a jeep that was rolled and had been sitting in my yard for a few years, partially exposed to the elements. As a result, whilst i have the system working (it blows ice cold), it only works through a switch i've installed directly yo the magnetic clutch.

I've replaced most of the various control modules beneath the dash, like for like, but the one thing tht confused me all along is the pressure switch beside the p/s battery. On the HDJ81, it had three wires entering and a three contact plug on the loom. The plug and wires on the HDJ80 only had two wires and two contacts. However, all the pressure switches listed online (for either model using toyodiy) have four contacts, not two or three.

Has anyone any idea what i'm missing?
OK, I am good with this, the pressure switch is a two stage design. Normally there are only two wires used but the switch connector can carry four, the first pressure part of the switch engages the compressor however, there is a second stage, this to bring in the optional electric booster fan that is standard in countries with hot climates, I actually use that second stage to bring on my electric engine cooling fan at half speed when the AC is switched on. The switch pigtails can be purchased and just push in and lock into the stock connector.