Electric Control Functions; Protection At Startup; Soft Startup; Outdoor Fan Motor Control - Haier H-MRV Series Service Manual

8. Electric control functions

8.1 Electric control functions of AU242FHBHA and AU482FIBHA
1. Startup control of compressor

1) Protection at startup

In order to prevent the constant startup of compressor, and keep the pressure balance of the
system, within 3 minutes after compressor shuts off, please do not enter the thermostat OFF state,
3 minutes later, if the unit is at thermostat ON state, the compressor can re-start up. In 10 minutes
after compressor shuts off, in order to keep pressure balance, the solenoid valve SV1 will open.

2) Soft startup

In order to protect the compressor and the transducer, when startup, the unit will decrease the
startup load. Entering condition:
In heating mode, after the 4-way valve operation is over, it enters soft startup.
After the defrosting is over in heating, it enters soft startup.

2. Outdoor fan motor control

1) If fan motor starts up at high speed, running for 30 seconds later, it will change speed.
2) Compressor shuts off, outdoor motor will shut off after running at low speed for 30 seconds.
3) Temperature control difference is ±1degree, the interval of speed change is over 45 seconds.
3. Heater control
If ambient temperature TA ≤27degree, heater will be electrified when compressor stops.
If TA ≥27degree, or when compressor starts up, heater is not electrified, the temp. difference is 5
degree.
4. Defrosting control
In heating mode, defrosting sensor TE will check the frost state of outdoor heat exchanger to
control the defrosting.
5. 4-way valve reliable operation control
1) Purpose: reliable conversion of 4-way valve
2) Startup control
a. If 4-way valve not being electrified before starup, the 4-way valve will convert directly. In
heating mode, after the outdoor unit receives the startup signal from indoor unit, the
compressor will start up and enter the soft startup period directly.
b. If 4-way valve is electrified before startup, the unit will enter reliable operation control.
6. Unloading valve SV1 control
According to the operation, the 2-way valve will be controlled as follows:
1) Before or after the compressor starts up, SV1 will make unloading operation. The detailed is the
following: SV1 opens 1 minutes before compressor starts up, and keep open in the soft startup
period until the soft startup is over; In other period and 10 minutes after the unit shuts off, SV1
opens.
2) Any protections, SV1 opens.
7. Refrigerant spray valve SV2 control
According to the compressor discharging overheat state, open time of SV2 will be controlled.
8. Discharging temperature sensor TD, suction temperature sensor TS
When compressor stops and in 5 minutes after the compressor starts up, the TD abnormal value is
ignored. TS is not ignored.
According to the temperature measured by TD, TS, the unit will make by-pass control when the
discharging temperature is overheat.
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