Mitsubishi PWFY-P36NMU-E-BU Service Handbook page 62

1. Phenomena
"HO" or "PLEASE WAIT" display on the remote controller does not disappear, and no operation is performed even
if the button is pressed. ("HO" or "PLEASE WAIT" display will normally turn off 5 minutes later after the power on.)
2. Cause
1) The power for the M-NET transmission line is not supplied from the outdoor unit.
2) Short-circuited transmission line
3) Incorrect wiring of the M-NET transmission line on the outdoor unit.
Disconnected wire for the MA remote controller or disconnected line to the terminal block.
The male power supply connectors on the multiple outdoor units are connected to the female power supply switch
connector (CN40).
In the system to which the power supply unit for transmission lines is connected, the male power supply connector
is connected to the female power supply switch connector (CN40) on the outdoor unit
4) Broken M-NET transmission line on the unit side
5) Faulty wiring or loose connector between the terminal block for M-NET transmission line connection (TB5) on the
unit and CM2M on the indoor unit circuit board
6) Incorrect wiring for the MA remote controller
Short-circuited wire for the MA remote controller
Disconnected wire for the MA remote controller (No.2) and disconnected line to the terminal block.
Reversed daisy-chain connection between groups
Incorrect wiring for the MA remote controller to the terminal block for transmission line connection (TB5) on the
indoor unit
The M-NET transmission line is connected incorrectly to the terminal block (TB13) for the MA remote controller.
7) The sub/main setting of the MA remote controller is set to sub.
8) 2 or more main MA remote controllers are connected.
9) Circuit board fault (MA remote controller communication circuit)
10) Remote controller failure
11) Outdoor unit failure
3. Check method and remedy
1) When 2) and 3) above apply, check code 7102 will be displayed on the self-diagnosis LED.
Same symptom for all units in a
system with one outdoor unit?
YES
Check the self-diagnosis LED
Is the error code 7102
displayed?
NO
Error found?
NO
Check (1).
NO
YES
Check
2 and 3.
Replace the M-NET remote
YES
controller with the MA
remote controller
Correct
the error.
- 59 -
Measure the voltages at the terminal
block for transmission line connection
(TB5) on the unit.
NO
17 - 30V?
Check 4.
Check for 5 and 6.
YES
Error found?
Correct
the error.
Circuit board fault or MA
remote controller error
YES
NO