High Pressure Switches

Specification of High Pressure Switches

A high pressure switch (HPS) and a low pressure switch (LPS) are protective devices for the compressor and refrigeration circuit. The high pressure switch monitors the system for an inoperative outdoor motor, and/or a dirty/restricted condenser (outdoor) coil. The low pressure switch monitors the refrigeration system for a loss of refrigerant charge, and may also be helpful in stopping the evaporator (indoor) coil from freezing up due to a dirty filter or low airflow over the coil. I say "may" because the low pressure switch cut-out setting could be set too low (15-20 lbs.) to be of any help. An evaporator coil could start to form ice at 30 lbs. low pressure charge.