R134a pressure question

[389driver]

Don’t put too much stock in those numbers. It looks like you’re working on a 379/389. I run a few of them. If it’s an orifice tube system it should cycle about once per minute at 85 degrees ambient with the engine idling at 1100-1200, the engine fan on, and the dash fan on high with the controls set on fresh air.

High side will be roughly 150-175. The low pressure should fluctuate between 25-40. When the compressor is running the low side should slowly draw down to 25 when the low pressure cutout switch will cycle the compressor off until the pressure rises back above 40.

At 85 degrees ambient this should occur about once per minute. The higher the ambient temp the less the compressor should cycle. Ideally at 100+ ambient the compressor should run continuously at 30-35 on the low side.