Midea MHC-96HWD1N1(A) Service Manual page 50

R410A Full DC Inverter Split Duct Type Technical Manual
1) L0 troubleshooting
Step 1: Compressor check
Measure the resistance between each two of U, V, W terminals of the compressor, all the resistance
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 to ground (Fig. C), all the
resistance should trend to infinity (Fig. D), otherwise the compressor has been malfunction, needs to be
replaced.
Fig. A
If the resistance value 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 of the local power supply voltage.
2) DC voltage between terminal 1 and 2 should be 510V～580V.
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 infinity. If any of the value
approximates to 0, the inverter module is damaged and should be replaced.
After replaced 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.
49
Fig.B
N
P
4
5
3
2
Fig.C
1
MCAC-UTSM-201503
Fig.D