Mitsubishi Electric PQHY-P72ZLMU-A Service Handbook page 361

[ IX Troubleshooting ]
(2) Troubleshooting transmission power circuit of heat source unit
Check the voltage at the indoor/heat source
transmission terminal block (TB3) of heat source unit.
DC 24 ~ 30 V
NO
Check the voltage at TB3 after removing transmission line from TB3.
DC 24 ~ 30 V
NO
Check whether the male connector is connected to
the female power supply connector (CN40).
NO
Connected
YES
Check voltage of terminal block for centralized control (TB7).
DC 24 ~ 30 V
NO
Check voltage of TB7 by removing transmission line from TB7.
DC 24 ~ 30 V
NO
Check the voltage between No.1 and No.2 pins of the
CN62 on the control board.
DC 24 ~ 30 V
NO
Check the voltage between No.1 and No.2 pins of the
CN102 on the power supply board for the transmission line.
DC 24 ~ 30 V
NO
Check the voltage between No.1 and No.3 pins of
the noise filter CN4.
DC270 ~ 356V
NO
Check the voltage between No.1 and No.3 pins of
the noise filter CN5.
DC270 ~ 356V
NO
Check the noise filter fuse F4 .
Fuse F4 on the noise filter board is blown.
NO
Check fuse F5.
Fuse F02 on the noise filter borad is blown.
NO
Check the voltages among TB21 and TB31 on the
noise filter
AC517.5 ~ 632.5V
NO
Check the voltage between L2 and L3 at the power supply
terminal block TB1.
AC517.5 ~ 632.5V
NO
HWE15150
YES
Check whether the transmission line is disconnected,
check for contact failure, and repair the problem.
YES
Check if the indoor/ heat source transmission line is not
short-circuited, and repair the problem.
YES Check the wiring between the control board and power supply board for the transmission
line (CN62, CNPS, CN102, CNIT), and check for proper connection of connectors.
YES
NO
Is there a wiring
error or a connector
disconnection?
YES
YES
Replace the control board.
YES Check the wiring between the control board and power supply board for the transmission
line (CN62, CNPS, CN102, CNIT), and check for proper connection of connectors.
YES
Is there a connector
disconnection?
NO
Check the voltage between No.5 and No.2 pins of the CNIT
on the control board.
NO
YES
Is the voltage
measurement between
4.5 and 5.2 VDC?
YES
Replace the control board.
YES
Replace the M-NET board
YES
Disconnect the noise filters CN4 and CN5, and then replace fuse F4 on the noise filter
board, then turn the power on.
Fuse F4 on the
noise filter board is blown.
NO
Connect the noise filter CN4, and then turn the power on.
Fuse F4 on the
noise filter board is blown.
NO
Replace the M-NET board
YES
Pull out CN4 and CN5 on the noise filter, replace fuse F02 on the noise filter board, and turn on the power.
Fuse F02 on the noise
filter board is blown.
NO
Connect the noise filter CN4, and then turn the power on.
Fuse F02 on the noise
filter board is blown.
NO
Replace the M-NET board
YES
Replace the noise filter.
YES
Replace the noise filter.
Check and fix any power supply wiring and main power supply problems found.
- 352 -
Fix the wiring and connector disconnection.
Check for shorted transmission line or power feed
collision for centralized control.
Fix the connector disconnection.
Replace the M-NET board
YES
Replace the noise filter.
YES
Replace the control board.
YES
Replace the noise filter.
YES
Replace the control board.
Turn on the
power again.
GB