Simple Check Methods For Inverter/ Compressor; Check Of Open Phase; Check Of Resistance (Transistor Module) - Mitsubishi Electric MSC-07RV Service Manual

Simple check methods for inverter/ compressor

F
Start
Disconnect the
compressor lead wire.
F Check of open phase
Balanced
H Check of compressor

Check of open phase

G
Be sure to use the analog tester for measurement.
• With the lead wire disconnected, activate the inverter and check the balance of voltage between terminals.
MXZ-18RV
Operation mode Operational frequency (Hz)
COOL
HEAT
MXZ-32RV
Operation mode Operational frequency (Hz)
COOL
HEAT
<Operation method>
Perform the test run in the heating mode by using the emergency run
switch on the indoor unit.
<Measure point>
Measure the AC voltages at the following three points on the transistor
module
• BLK - WHT
• BLK - RED
• WHT - RED
<Judgment>
Balanced : Normal
Unbalanced : Faulty (Open phase)
Shut off by overcurrent : Faulty (Short)
NOTE 1 : After the outdoor fan starts running, wait for one minute or more before measuring the voltages.
NOTE 2 : The output voltage values in the above table have the tolerance of ± 20%.

Check of resistance (transistor module)

H
• Disconnect the lead wires and check the resistance of terminals at the transistor module.
<Measure points>
Measure the AC voltage at the following six points on the transistor module.
BLK - WHT, WHT - BLK
BLK - RED, RED - BLK
WHT - RED, RED - WHT
<Judgment>
Infinite (Ω) : Normal
Zero to dozens (Ω) : Faulty (Short)
Unbalanced
GCheck the resistance of
the transistor module.
Replace the transistor
module and outdoor
controll P.C. board in a set.
<MXZ-18/32RV>
Output voltage (V)
58 110
58 70
Output voltage (V)
58 110
40 70
<MXZ-18/32RV>
Infinite
Replace the outdoor
controll P.C. board.
0 '
Tester indication
BLK-WHT
ACV
300
BLK-WHT
ACV
300
<MXZ-18/32RV>
136
BLK-RED WHT-RED
Normal
(balanced)
ACV ACV
300 300
BLK-RED WHT-RED
Faulty
(unbalanced)
ACV ACV
300 300
Tester indication
Normal
(Infinite)
X1
Faulty
(Zero to dozens of ohms)
X1