Protection; Fan-Only Mode - Midea MSC-09HRDN1-QD0(E) Service Manual

9.2.2 LED display control function.
Pressing "LED display" button on remote controller will turn off all displays on indoor unit, while pressing once
again, all displays will resume.
9.2.3 Display function in outdoor unit.

9.3 Protection

9.3.1 Three Minutes Delay at restart for compressor.
9.3.2 Temperature protection of compressor top.
9.3.3 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.
9.3.4 Temperature protection of compressor exhaust.
a) Initialize temperature of compressor as Tex, if 108＜Tex＜115℃, the speed of compressor will be restrict and
descend one grade every 3 minutes till 1870rpm for 9K(1829rpm for 12K), then the speed will not be changed
until Tex＜105℃. When Tex＜90℃, the restriction can be released.
b) If Tex≥115℃ for 5 seconds, the compressor will stop, and the units can not restart until Tex＜90℃.
9.3.5 Inverter module Protection, Inverter module Protection itself has a protection function against current, voltage and
temperature. If these protections happened, the the corresponding code will display on indoor unit LED.
9.3.6 Sensor protection at open circuit and breaking disconnection
9.3.7 Fan Speed is out of control. When Indoor Fan Speed is too low (lower than 300RPM for 60 seconds), the unit
stops and LED displays failure information and can't return to normal operation automatically.
9.3.8 Cross Zero signal error warning. If there are 20 alternations of Cross Zero signals are incorrect, the unit stops and
LED displays failure information. After resuming, the motor rotates again. The spacing of Cross Zero signal is
6-13ms.
9.3.9 Indoor fan delayed open function
9.3.10 For all modes, when the units are turned on, the indoor fan can operate 10 seconds after the action of louver.
9.3.11 Compressor preheating function.compressor heating cable.
1) Preheating permitting condition:
After OPMR (Outdoor Power Main Relay) closing, 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.
2) Preheating mode:
A weak current flows through the coil of compressor from the wiring terminal of compressor, then the
compressor is heated without operation.
3) Preheating release condition:
If T4＞5℃ or user turns on the machine and compressor runs, preheating function will stop.
9.3.12 Compressor heating cable
If outdoor temperature(sensed by outdoor thermostat) is lower than 5℃, the thermostat closes and compressor
heating cable begins to work. If outdoor temperature is higher than 15℃, the thermostat opens and compressor
heating cable stopping working.

9.4 Fan-Only Mode

9.4.1 In fan-only mode, compressor and outdoor fan keep off. For the action of 4-way valve please refer the passage
9.10.
9.4.2 Temperature setting function is disabled, and no setting temperature display.
24