Tripac APU Code 10. High Discharge Pressure.

Too much freon in the system? Check pressure (when compressor is activated) and see if it's too high (above 30-35)

Target pressure is 28-38 (?)
Component Description and Location.

The high pressure cutout switch is located on the receiver/dryer.

How alarm is set.

HCPO switch opens at 360 psig (2482 kPa) and closes at 240 psig (1655 kPa) 

Diagnostic Procedure.

1. Check the refrigeration system for high discharge pressure and correct as needed.

2. Check the High Pressure Cutout switch for proper operation (closed under normal conditions). Check the switch for excessive reistance. The nominal switch resistance is less than 1 ohm.

3. Check the High Pressure Cutout switch circuit as shown by Service Procedure D01A.