For the defrost timer working principle will analyze two points;
1. When the air conditioning is running, the defrost thermostat detects the temperature of the outdoor heat exchanger. When the outdoor temperature is lower than the set temperature to remove the frost thermostat contacts 2 a l off, 2-3 closed,
Air conditioning defrost timer motor power to start timing; Defrost Timer Relay when the set temperature, the defrost timer contacts 2-3 off, 1-2 connected, defrost timer motor power to stop timing.
At this time the electromagnetic four-way valve coil and fan motor at the same time off, stop running, the compressor cooling operation, outdoor defrost.
2. Air conditioning defrost, the outdoor heat exchanger temperature rise. When the defrost thermostat reset temperature is reached, the defrost timer 2 • 3 is open, 2-1 is closed, and the electromagnetic four-way valve coil and fan motor are energized.
After the end of the defrost, restore the system at the same time defrost timer motor power again, Defrost Timer Relay for the next defrost to prepare.
In the air conditioning service will do a lot of analysis, there is time to see the window air conditioner circuit works so that you not only hanging,
Cabinet air conditioning to understand more, window type also understand.
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 Step 1: Unplug 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. 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; Defrost Timer Relay if the pointer goes to another position, the defrost timer is faulty. Replace it with a new timer of the same type.