High Pressure Safety Valve HVAC: Description and Operation

HIGH PRESSURE RELIEF VALVE
The high pressure relief valve is located on the rear surface of the compressor housing. This mechanical valve is designed to vent refrigerant from the system to protect against damage to the compressor and other system components, caused by condenser air flow restriction or an overcharge of refrigerant.

The high pressure relief valve vents the system when a discharge pressure of 3445 to 4135 kPa (500 to 600 psi) or above is reached. The valve closes with a minimum discharge pressure of 2756 kPa (400 psi) is reached.

The high pressure relief valve is only serviced as part of the compressor assembly, and must not be removed or otherwise disturbed.

The high pressure relief valve vents only enough refrigerant to reduce the system pressure, and then re-seats itself. The majority of the refrigerant is conserved in the system. If the valve vents refrigerant, it does not mean the valve is faulty.

On new compressor assemblies, a mylar disc is applied to the venting port of the valve. The disc is primarily intended for protection of the valve during the painting operation. A missing or damaged disc does not indicate failure. If the mylar disc has loosened or come off, apply a drop or two of refrigerant oil into the valve mechanism through the venting holes. This will prevent salt, dirt, or moisture from affecting the operation of the valve.