Haier HB21FWRSS Service Manual - page 25
Electrical Control Principle
1. Overview
HB21FW refrigerator electrical control principle:
Whole wind cooling design, with controlling of fixed frequency compressor.
Temperature in the fridge is controlled by the fridge sensor R controlling the switch of the air
escaper..
Temperature in the freezer is controlled by the freezer sensor F controlling the operating of
the compressor.
Ice making operates by icemaker sensor and main control board, which control the cycle of
ice pushing.
2.Main Control Board of HB21FW
There are 13 socket connectors on the main control board of HB21FW
First, let’s look at the socket connector:
CN1 is the socket connector for the fridge, parts from left to right are:
1-2 Connect to fridge sensor. We can check the resistance of fridge sensor by tests these
two wires. The resistance range of fridge sensor should be 6.35-3.88KΩ if it works right
(correspond to 0℃-10℃).The resistance range should be 2.45-1.58 KΩ at regular temperature
(correspond to 20℃-30℃).
3-4 Connect to the fridge door switch. They are connected when the door is open, and
disconnected when it is shut.
5-6 Heater of fridge air escaper. Measurement of the two wires gives the output voltage
(DC 12V) and the resistance (144Ω±10%) of the heater;
7-10 Connect to air escaper motor.
CN2/CN3 are the socket connecting cabinet display panel.
CN4 Parts from left to right are,
1-2 Connect to Freezer sensor. We can check the resistance of freezer sensor by tests
these two wires. The resistance range of freezer sensor should be 10.9-25.19KΩ if it works right
(correspond to -10℃- -25℃).The resistance range should be 2.49-1.61 KΩ at regular
temperature (correspond to 20℃-30℃).
3-4 Connect to the defrost sensor; Measurement is same as freezer sensor.
5-6 Connect to the freezer door switch. They are connected when the door is open, and
disconnected when it is shut.
7-9 Connect to cooling fan motor. Measurement of the 8-9 two wires gives the output
voltage (DC 11-13V) of the cooling fan motor.
10-12 Connect to freezer motor. Measurement of the 11-12 two wires gives the output
voltage (DC 11-15V) of the freezer motor.
CN5 is the socket connector for the display panel on the door, parts from left to right are:
3