Protection; Fan-Only Mode - Midea MSY-09HRDN1-QC8 Service Manual

8.3 Protection

8.3.1 Three Minutes Delay at restart for compressor.
8.3.2 Temperature protection of compressor top.
If the temperature of compressor top is too high (higher than 115℃ and the Over-load Protector is
cut, the units stop. When the Over-load Protector restore and close (lower than 100℃), the
compressor will restart (In this case the compressor is restricted by Three Minutes Delay protection.)
8.3.3 Temperature protection of compressor exhaust.
If the exhaust temp. of compressor is higher than 115℃ and lasts for 5 seconds, the compressor stops
and does not resume until the exhaust temp. is lower than 90℃.
8.3.4 Inverter module Protection, Inverter module Protection itself has a protection function against
current, voltage and temperature. If these protections happened, the corresponding code will
display on indoor unit LED.
8.3.5 Sensor protection at open circuit and breaking disconnection
8.3.6 Fan Speed is out of control. When Indoor Fan Speed is too low (lower than 300RPM for 50
seconds), the unit stops and LED displays failure information and can't return to normal operation
automatically.
8.3.7 Zero-crossing signal error warning.
If there is no zero-crossing signal in 4 minutes or the interval is wrong, the unit will enter error warning.
8.3.8 For all modes, when the units are turned on, the indoor fan can operate 10 seconds after the
action of louver.
8.3.9 Compressor preheating function.
Preheating permitting condition:
If T4(outdoor ambient temperature)＜3℃ and the machine connects to power supply newly or if T4
＜3℃ and compressor has stopped for over 3 hours, the compressor heating cable will work.
Preheating mode:
A weak current flow through the coil of compressor from the wiring terminal of compressor, then the
compressor is heated without operation.
Preheating release condition:
If T4＞5℃ or user turns on the machine and compressor runs, preheating function will stop.

8.4 Fan-Only Mode

8.4.1 Temperature setting function is disabled, and no setting temperature display.
8.4.2 In this mode, the action of louver is the same as in cooling mode.
8.4.3 The action of auto fan in fan-only mode is the same as auto fan in cooling mode with 24℃
setting temperature.
℃
3.
3.
1.
1.
high
mediu
low
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