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Defrost Timer Defrosting Principle

Jul 13, 2017

Defrost timer refers to the refrigerator in the defrost process, do not need to operate any button or switch, you can automatically complete a series of defrost operations. Defrost timer generally has three forms: the basic automatic defrost device, the cumulative type of automatic defrost device, Defrost Timer Relay automatic defrost device. The timer used in the fully automatic defrosting device is called a defrost timer, which consists of a micro motor, a gearbox, a cam, a movable contact and a stationary contact, and the outside is provided with four terminals and one hand Knob.

The defrost timer contact action time in the circuit is set at every 8h (depending on the manufacturer's design, time varies).

After the compressor is running for 8 hours, the defrost timer disconnects the circuit to the compressor, turns on the bimetallic defrosting thermostat and defrost heater circuit, Defrost Timer Relay and begins to heat the defroster. Defrost timer control defrost time is generally 15 ~ 30min.

After the frost of the evaporator surface melts, the temperature inside the tank rises to 10 to 16 ° C, the bimetallic defrost thermostat turns off the defrost contact, and the defrost heater stops heating, and the defrost timer starts at the next Cycle timing.

How to repair defrost timer

If the compressor is not running, it may be that the defrost timer has failed. This part is located near the compressor. The method for detecting the defrost timer is as follows:

1 Unplug the power of the refrigerator.

2 Step 2: Disconnect the wires between the timer and the timer motor. Unscrew the two set screws and remove the timer from the bracket.

3 Step 3: Set the multimeter to RX1 to detect the defrost timer. Defrost Timer Relay Place the two probes of the multimeter on the two wires of the defrost timer (not the motor), and then turn the timer's screw control shaft until it clicks. If there is no problem with the defrost timer, the meter's reading should be zero; if the pointer goes to another position, the defrost timer is faulty. Replace it with a new timer of the same type.