Can anyone shed a little light on how the power should run from the relay to engage the clutch in the compressor? I replaced the compressor since the old one wouldn’t engage and it was worn out. It never worked and now I’m finding out I didn’t have power to the pressure switch to even kick it on. Tried vacuuming down and adding Freon but still won’t get power.

 

got to be the ac relay... right?

 

That was my initial thought as well but swapping it out for another known good relay didn’t do the trick.

 

you check the continuity on all the wiring?

should be easy to do using the wiring diagrams.

 

The magnetic clutch gets power from the refrigerant temperature switch which is part of the compressor. The temperature switch gets power from the switching side of the A/C relay. The switching side of the A/C relay gets power from fuse 9 in the relay box (evo 8). The control side of the A/C relay gets power from the ignition switch by way of fuse 5 (evo 8) on the junction block. The coil in the control side of the A/C relay is activated (relay is closed) when it has a ground supplied by the engine ECU. The blower switch, inlet and outlet thermo sensors, the outside air damper and the A/C controls are connected to the A/C ECU. The A/C ECU has two wires that connect to the engine ECU, one through the pressure switch. So, when all is right with the world, the engine ECU supplies a ground, the A/C relay closes and the system runs.

 

very nice...