Midea V4 Plus S Series - L0 Troubleshooting

R410A All DC Inverter V4+S Series 60Hz MCAC-VTSM-2015-09
150 Troubleshooting
1) L0 troubleshooting
Step 1: Compressor check
Measure the resistance between each two of U, V, W terminals of the compressor, all resistance levels should
be the same and equal to 0.9~5 Ohms. (Fig. A and Fig. B)
Measure the resistance between each of U, V, W terminals of the compressor and ground (Fig. C), all the
resistance should be infinite (Fig. D), otherwise the compressor has malfunctioned and needs to be replaced.
Fig. A
Fig.B
Fig.C
Fig.D
If the resistance values are normal, then go to step 2.
Step 2: Module check
1) DC voltage between terminal P and terminal N should be 1.41 times the local power supply voltage.
2) DC voltage between terminal 1 and 2 should be 270V～360V.
3) Disconnect the terminal 3, 4, and 5 from inverter compressor. Measure the risistance between any two
terminals among terminal 1, 2, 3, 4, 5. All the values should be infinite. If any of the value approximates to 0,
the inverter module is damaged and should be replaced.
After replacing the inverter module, if the system is still abnormal, then go to step 3.
Step 3: DC generatrix check
Direction of the current in DC supply wire which is running through the inductor should be the same as the
direction of arrow marked on the inductor.
1
2
3
4
5
P
N