Here's what I have learned and can therefore suggest.

1) Systems using r134a are very particular about having the precise amount of refrigerant. Too much or too little and things don't work right.

2) The S/V90 and 960 (1997 and other years) use a system that has no high pressure port so testing pressures is not done by normal means, if at all.

3) The only way to learn if the charge is OK is to do a evacuate and re-charge job. When my shop did mine, they found it a little low, likely from my tampering. They filtered the refrigerant and added compressor oil and then re-charged the system to the amount specified . No improvement.

4) The ACC system is such that with the "Blue square" pushed, the compressor can run all the time. It will run until the low pressure switch (on the receiver) opens. The pressure will then rise to a point that allows the switch to close, and the compressor starts. Adjusting the temp setting knob merely varys the air intake percentage of heated air vs chilled air, not the compressor run time.

All this makes my years of experience with the 240 system pretty much useless.

I replaced both the low pressure switch and the high pressure switch (lower right corner of the front of the condenser), which had only the effect of making them not suspects. When the compressor is running the air vents blow cold enough to be too cold in 98F heat in a black car, so the compressor itself is OK.

What's left is either the clutch clearance OR low voltage, since the clutch is not engaging. Could also be the high-temp switch on the compressor.

Get the evac and recharge done, and move on from there. It was about $135 for me.

Good Luck,

Bob

:>)