Defrost Termination Switch (mechanized)

TM 10-4110-262-13&P

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Defrost Termination Switch (mechanized)

The Defrost Termination switch is mounted in the evaporator coil and controls the defrost cycle in

response to the evaporator coil temperature. The switch is closed when the evaporator coil temperature

is below 36 F, completing the defrost circuit to ground and preparing the electrical system for the defrost

cycle.

When the unit does shift into a defrost cycle, the evaporator and condenser fan stop, and heat from the

hot refrigerant gas melts the frost from the evaporator coil. The switch opens and terminates the defrost

cycle when the evaporator coil temperature rises above 48 F ( 5 F).

Defrost Relay

The Defrost relay controls operation of the defrost cycle. When the Defrost Timer or the Manual Defrost

switch completes the circuit through the defrost termination switch to ground, the defrost relay is

energized. This energizes the Solenoid Valve and de-energizes the fan relay.

The defrost relay stays energized until the defrost cycle is terminated by the defrost termination switch or

the On/Off switch is pressed.

Defrost Solenoid Valve

The hot gas valve is an electrical valve that controls the flow of refrigerant through the refrigeration

system.

When Solenoid Valve PS is energized, the hot gas valve is opened and it routes hot refrigerant gas to the

evaporator.

END OF WORK PACKAGE

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