Refrigerant System Protection

A/C Compressor Pressure Relief Valve

An A/C compressor pressure relief valve (19D644) :

• Prevents excessive high-pressure buildup of 3102 kPa and above (450 psi and above).
• Also prevents damage to the A/C compressor (19703) and other system components.

A/C Pressure Cut-Off Switch

The A/C pressure cut-off switch (19D594) is located in the discharge line between the A/C compressor and A/C condenser core (19712) . The A/C pressure cut-off switch has two sets of contacts. One electrical contact is normally closed. When compressor head pressure rises to approximately 2896 kPa (420 psi), the contacts open and the compressor operation is shut off. When head pressure drops to approximately 1724 kPa (250 psi), the contacts again close and allow operation of the A/C compressor . Shutting down compressor operation prior to the pressure relief valve set point 3103 kPa (450 psi) ensures containment of the refrigerant in the A/C system.

The switch contains a second set of electrical contacts for the high speed radiator electric motor which are normally open. When discharge line pressure reaches approximately 2241 kPa (325 psi), these contacts close and engage the high speed fan. When pressure drops to approximately 1896 kPa (275 psi), the contacts again open and the high speed fan is disengaged.