Daikin VRV S RXQ4/5ARV1 - Power Transistor Check

Check SiAF332111E
340 Part 6 Service Diagnosis
6.4 Power Transistor Check
CHECK 4 RXQ4/5AR, RXMQ10/12AR
Use a multimeter to measure the resistance to determine if the power transistor is defective or
not.
1. Do not touch live parts (high voltage parts) within 10 minutes after turning off the power
supply.
2. Touch the earth terminal with your hand to release static electricity. (This is to avoid
damaging the PCB.)
3. Use a multimeter to measure the C+ and C- on the PCB to make sure that the residual
voltage of the power transistor is under 50 VDC.
4. After verifying the residual voltage, pull out the outdoor fan motor connector.
If a strong wind causes the outdoor fan to rotate, the capacitor may store electricity.
Therefore, make sure that the fan is still and then pull out the outdoor fan motor connector.
5. Disconnect the relay connector (X502A) between the power transistor and the compressor.
Make sure there is no deformation of the Faston terminals.
6. Use a multimeter to measure the resistance listed in the table.
Among the three phases listed in the table, if there is one phase with unbalanced resistance
(with a value five times higher than the other values), then the power transistor is defective.
When normal, all phases have the same resistance value.
Multimeter Resistance Multimeter Resistance
Red (+) Black (-) Red (+) Black (-)
C+ U C– U
C+ V C– V
C+ W C– W
UC+ UC–
VC+ VC–
WC+ WC–
4/5 HP models
Blue White Red
Blue White Red
Outdoor unit PCB
Compressor
10/12 HP models
Blue White Red
Outdoor unit PCB
Compressor