Midea M-Thermal Series Service Manual page 73

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M‐Thermal Split

Table 4‐4.2: Errors indicated on LED1/2

Flashes 8 times and stops for 1 second, then repeats

Flashes 9 times and stops for 1 second, then repeats

Flashes 10 times and stops for 1 second, then repeats

Flashes 12 times and stops for 1 second, then repeats

Flashes 13 times and stops for 1 second, then repeats

Flashes 15 times and stops for 1 second, then repeats

Flashes 16 times and stops for 1 second, then repeats

Flashes 17 times and stops for 1 second, then repeats

Principle of DC inverter

Power

Bridge

supply

rectifier

(220V AC)

○

① 220V AC power supply change to DC power supply after bridge rectifier.

② Contactor is open, the current across the PTC to charge capacitor, after 5 seconds the contactor closed.

③The capacitor output steady power supply for inverter module P N terminals. In standby the voltage between P and N

terminal on inverter module is 310V DC. When the fan motor is running, the voltage between P and N terminal on

inverter module is 380V DC.

L0/L4 troubleshooting

Situation 1: L0 or L4 error appears immediately after the outdoor unit is powered‐on

Inverter module is damaged

Notes:

Measure the resistance between each of U, V and W and each of P and N on the inverter module. All the resistances should be infinite. If any of them are

not infinite, the inverter module is damaged and should be replaced. Refer to

When replacing an inverter module, a layer of thermally conductive silica gel should be painted on the IPM module, IGBT, diode, brigde rectifier (on the

reverse side of the inverter module). Refer to Figure 4‐4.1.

LED1/2 flashing pattern

PTC

Contactor

L0 / L4

Midea CAC Confidential

Corresponding error

L0 ‐ Inverter module protection

L1 ‐ DC bus low voltage protection

L2 ‐ DC bus high voltage protection

L4 ‐ MCE error

L5 ‐ Zero speed protection