Unit Protection Devices

High Pressure Cutout Switch: The high pressure cutout switch is located on the compressor discharge manifold. If the compressor discharge pressure becomes excessive, the switch opens the circuit to the run relay to stop the unit. The microprocessor will record an alarm code.

High Pressure Relief Valve: This valve is designed to relieve excessive pressure in the refrigeration system. It is located on the receiver tank. If the high pressure relief valve opens, much of the refrigerant will be lost. Take the unit to a Thermo King dealer if this occurs.

Overload Relay - Automatic Reset: An overload relay protects the CMG - Combined Motor Generator. The overload relay opens the circuit to the electric motor if the motor overloads for any reason (e.g., low line voltage or improper power supply) while the unit is on electric standby operation. the A-Series Controller records an alarm code.

Smart FETs: Smart FETs in the microprocessor protect some circuits and components from an overcurrent condition.

Fuses: Fuses are located in harnesses and in the Power Distribution Module (PDM). All fuses must be serviced only by qualified Thermo King technicians. Contact your nearest Thermo King Dealer for assistance.