Notes:   
1.  Low pressure switch connection is port CN17 on the main PCB. 
2.  An insufficiency of refrigerant causes compressor discharge temperature to be higher than normal, discharge and suction pressures 
to be lower than normal and compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. 
These issues disappear once sufficient refrigerant has been charged into the system. 
3.  A low pressure side blockage causes compressor discharge temperature to be higher than normal, suction pressure to be lower 
than normal and compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. For normal 
system parameters. 
4.  Outlet water temperature sensor (TW-out) connection is port CN10 on the main PCB  
5.  Measure the resistance among the three terminals of the pressure sensor. If the resistance is of the order of mega Ohms or infinite, the pressure sensor has 
failed. 
 
 Protection logic 
 
When P0 protection occurs 3 times in 60 minutes, the HP error is displayed. When an HP error occurs, a manual system 
restart is required before the system can resume operation. 
 
Note: 
Pe: Suction pressure