In the factory 97 wiring, the purple goes from the dash control to the low pressure cycling switch and then (as red/yellow) to the high pressure safety switch and then (as dark green/orange) to the WAC (WOT AC cutoff) relay and then (as black/yellow) to the compressor clutch.

 

cool i will check the voltages at each location.......is the relay located in the fuse box under the hood?

could it be a bad pressure switch or relay that is doing the cutout? because if i am getting power to my efan and the purple wire is ohming out to the low pressure safety switch (check that a couple days ago), then i must be something ahead of the EATC unit then shouldn't it?

even if i put the 2 purple wire together (off the "rear fan off" switch relay), the A/C still doesn't come on...........

 

Yeah, those pressure switches and the relay are in series before the compressor clutch. So, if there is a problem at any one of them, the A/C compressor cannot operate.

 

is it common that they go bad?

i will try jumping the pressure switches with a 12v from the battery, and then i have already jumped the relay from the battery to the clutch, so i know that works........i wonder how much (and how easy) the switches are to replace?

 

alright.....the purple wire is putting out ONLY 12v with the EATC HU in the A/C position.....everything works fine when i jump from the battery to the compressor with 13.8v.......could it be the EATC HU isn't putting out the amps/volts that the compressor clutch needs to engage?

is there a way to get the battery voltage/amps to the purple wire via relay to try that? i have a SPST relay here, and if need be, i dont have to have the "rear fan off" button do anything (i can add a purple wire interruptor switch with no problem)........

 

Well, if the purple wire has 12 volts with the A/C on, that's OK and you know that the compressor works when jumped with roughly 12 volts. So that means that the current path is broken somewhere in between, like at one of the 2 pressure switches or at the relay or the wires that connect them. It seems like you should be able to work your way down the path I gave you until you find the disconnect.

 

i ohmed out all the wires from the purple wire from the EATC to the clutch coil.....everything checked out ok.....

it is weird, cause the compressor isn't running at full potential (i don't think anyways)....seems like it is bogging down or something.....could that mean the system is low on freon, or would the compressor plug (from the relay) not have any voltage at all when the A/C was on?

 

i have 12v at the compressor clutch when the A/C is on.......the same as the purple wire has.....just the clutch wont engage.....it is a brand new clutch and coil.....

 

got the A/C to work with the EATC finally............i had to put on another relay for the purple wire.....i use a SPST relay and wired it like this:

pin 30 = 15amp circuit off battery
pin 87 = purple wire to "rear fan off" function relay (or to carry the power to the low pressure switch)
pin 86 = ground
pin 85 = purple wire from EATC headunit.....

works like a dream now!