| Here is the steps I have taken so far.. on the ECU 2 important pins
* pin 46 is your A/C input to the ECU (test it to see if see ground) also it should cycle on and off when you go from econ and full auto I am assuming you have a full auto AC system. If you have a manual AC unit you may have a bad thermo control amplifier I couldn't find one for sale but I now realize that 94+ systems use so maybe it is available under another part number. * pin 9 is the output from the ECU to eventually the relay that is triggered by GND output. Step 1. Check GND on input pin 46 "sky blue" (if no go you got a problem coming from the controller).. I had a working circuit so I continued on Step 2. Check for GND on Pin 9 (orange) this output pin if you have ground signal and your AC clutch is still not engaging go to next step Step 3. do a continuity test between Pin 9 from the ECU and connect F25 this is the brown connector next to the fuse box its an orange wire on the left 2nd terminal from the top, I did this by unplugging the terminal. If this works for you then congrats because this is wear I am having trouble and I think my main harness has a problem and I am going to have to either unwire my harness or buy a new one or run a new wire. Step 4. Is to check from that point on you need to the low pressure sensor that under center cowl and see if you can get gnd on orange wire. E44 is the location and connector Step 5. Check to see if you jumper E44 if you clutch starts to work you most likely got a bad low pressure switch a common fail about $25-30 for it but you need to have your system vacuumed and refilled. Step 5a. if you want to the rest of the circuit you can the light green blue wire to gnd and it should kick your compressor on. Do this step confirms that AC compressor works, and that your relay works and the rest of the connections are working. Step 6. if you Step 5a didn't work start working on the relay section at the fuse panel under the hood. You can jumper here as well to see if the clutch activates. If the clutch activates then check the wiring going back to the E44 to see if you don't have a break, if it is ok and pin 5 of the relay box shows a GND signal then you bad relay..
Step 7. Retarded POS AC system from far below still doesn't work then your problem is on the AC compressor itself things to look is to see if the wire has a break or cut . Cuts usually happen from the wire rubbing on the AC Accessory belt. Or you had a bad clutch.
Please be aware that I am diagnosing my own system that was working at one time and now stopped as well. I have the problem where I think it is the engine harness but I could be missing a step or so. Check these pages
[ http://z32.wikispaces.com/Air+Conditioning+System ] I used the FSM as well to look at the electrical system diagram and circuit switch. Please note if you have an AUTO AC system or a manual one and the year of your vehicle.
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