My 960's AC compressor cuts off above 45-50MPH on the highway, engine speed about 2400 RPM. The blower motor is fine, by the way - no reduction in airflow from the vents - just a loss of cooling like the compressor is shutting down. As a test I drove around the block in first gear at 3000RPM and the AC was cold, so it must be vehicle speed related.
Question is, why should the compressor operation be related to the vehicle speed and is there a way to solve this mystery?