Haier H-MRV AF092FCBHA, Service Manual

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9. Heat exchanger temperature sensor TE, which will work in defrosting
1) According to temp. measured by TE, make the defrosting operation.
2) According to temp. measured by TE, make the fan speed control in heating.
10. Oil return operation in cooling
When indoor unit receives oil return signal, oil return operation will begin.
The compressor will keep a certain frequency, and quit 4 minutes later, then sends oil return over
signal to indoor unit.
11. Refrigerant return control in heating
In this operation, compressor keeps running and some indoor thermostats are OFF for 60 minutes,
also meets the other conditions, the function will work.
12. Remains heating operation ( used to protect compressor)
Purpose: avoid too much refrigerant stays in gas-liquid segregator, which results in compressor
difficult startup the next time.
In heating mode, after outdoor receives the shutoff signal from indoor, the unit will enter remains
heating operation ( the shutoff which results from communication malfunction between indoor and
outdoor, needs remains operation; the other protective shutoff will not make remains operation.)
13. Rating operation (only in debugging)
Rating operation: indoor capacity is fixed, compressor frequency depends on the total indoor
capacity and can be adjusted by hand.
In this period, the frequency can be increased or reduced.
14. Current value has 3 stages. Current is over A, frequency will increase to the target frequency;
Current is between B and C, frequency will decrease; current is below B, at the beginning, it not
rises, then rise slowly, when it is over B, stop rising to decrease frequency operation.
Peak current is over C and keep it for a period, the unit will be standby state, meanwhile, sends out
the failure signal. If running for another 30 minutes, current is over C again for a period, the
compressor stops, and sends out failure signal.
15. High pressure switch protection
If the pressure switch output is 1 (high level), there is no protection.
If the pressure switch output is 0 (low level) for a period, the unit enters high pressure protection.
Compressor will stop and send out alarm signal. The alarm is solved, the system can resume, in 3
minutes when compressor is standby, there is still alarm.
16. Low pressure switch protection
If the pressure switch output is 1 (high level), there is no protection.
When compressor is running, if low pressure switch is OFF for 3 minutes, the unit will alarm. When
compressor stops, if low pressure switch is OFF for 30 seconds, the unit will alarm. When
compressor starts up, in 3 minutes, low pressure switch is shielded. In defrosting and within 6
minutes when defrosting is over, low pressure switch is shielded.
17. Time shorting function (usually used in debugging)
As long as one indoor unit is in time shorting, the outdoor will enter 1/60 second time shorting
function. Outdoor is equipped with timeshorting port, if this port is disconnected, it will enter time
shorting too.
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