Midea MA9A-24HR-QB4W, Service Manual

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8.3 Main Protection
8.3.1 Time Delay at restart for compressor.
8.3.2 Fan Speed is out of control.(except MS9A-21HR-QB6W and MA9A-24HR-QB4W models)
----When Indoor Fan Speed keeps too low or too high for certain time, the unit will stop and the LED
will display the failure
8.3.3 Current protection
I3SEC
I5MIN
A
B
C
Resume
IFAN
IRESTORE
A zone : The current exceeds I
3SEC
for 5 seconds, the compressor and outdoor fan will shut off.
B zone: The current exceeds I
5min
for 5 minutes, the compressor and outdoor fan will shut off.
C zone: The current exceeds I
FAN
, the outdoor fan will shut off if AC is in heating mode. If AC is in
cooling mode, the indoor fan will run at low speed.
8.3.4 Zero crossing detection error protection(except MS9A-21HR-QB6W and
MA9A-24HR-QB4W models)
If AC can not detect zero crossing signal for 4 minutes or the zero crossing signal time interval is not
correct, the unit will stop and the LED will display the failure. The correct zero crossing signal time
interval should be between 6-13ms.