My '87 GN AC just stopped working. I tried a hot wire from the battery to the clutch coil connector and got nothing. I assume it is the coil. When I converted the car to R134 5 years ago, I just replaced the entire compressor. Is there a "how to" for changing just the clutch with the compressor on the car? I think Auto Zone loans any special tools needed when you buy the parts from them. How much of a job is this?