M thermal Mono
70 202008
Midea M thermal Mono
L0 troubleshooting 4.20.6
Situation 1: L0 error appears immediately after the outdoor unit is powered-on
L0
Communication wire between refrigerant
system main control board for refrigerant
systemnd inverter module (4 pins) not
connected properly
1
Yes
Ensure communication wire is connected
properly
No
Inverter module is damaged
2
Yes
No
Voltage between pins F0 and GND of
communication port for connection to
inverter module on the refrigerant
system main PCB is too low
3
Yes
Replace the inverter module
4
Notes:
1. The communication port between refrigerant system main control board for refrigerant system inverter module is port CN36 on refrigerant system main
control board for refrigerant system port CN8 on inverter module.
2. 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.
3. The normal voltage between F0 and GND is 5V. Refer to Figure 4-4.2.
4. When replacing an inverter module, a layer of thermally conductive silica gel should be painted on the IPM module (on the reverse side of the inverter
module PCB). Refer to Figure 4-4.3.
Figure 4-4.2: F0 and GND voltage on IC28-1 F0 IC28-4 GND
Vnormal = 5V
Figure 4-4.3: Replacing an inverter module
IPM
IC28-1 F0
IC28-4 GND
Midea CAC
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