Mitsubishi Electric PQHY-P72ZLMU-A Service Handbook page 173

[ VII Control ]
(2) Heat source unit (cooling and heating modes)
"HO" / "PLEASE WAIT" blinks on
the remote controller
1. Protection function self-holding cancelled.
2. LEV1 fully closed.
1. 72C OFF
2. Inverter output 0Hz
3. All solenoid valves OFF
Refer to Cooling/Dry
Operation 2-(1) and 2-(3)
For about 3 minutes after power on, search for the indoor unit address, for the remote controller address,
*Note 1.
and for the group information will start. During this, "HO" / "PLEASE WAIT" blinks on the display of the remote
controller. When the indoor unit to be controlled by the remote controller is missing, "HO" / "PLEASE WAIT" keeps
blinking on the display of the remote controller even after 3 or more minutes after power on.
The system may go into the error mode on either the indoor unit or the heat source unit side. The heat source unit
*Note 2.
stops only when all of the connected indoor units are experiencing problems. The operation of even a single indoor
unit will keep the heat source unit running. The error will be indicated on the LED display.
The heat source unit operates according to the operation mode commanded by the indoor unit. However, when the
*Note 3.
heat source unit is running a cooling operation, come of the operating indoor units will stop, or the operation of these
indoor units will be prohibited even when the indoor unit mode is switched from fan mode to heating mode.
This also applies when the heat source unit is running a heating operation.
HWE15150
Start
NO
Breaker
turned on
YES
*Note 1
Indoor units
registered to the
remote controller
NO
YES
2
From indoor unit
NO
Operation
command
YES
Operation
mode
Cooling / Heating
*Note 2
YES
Error mode
NO
72C ON
*Note 3
Operation
mode
Refer to heating
Operation 2-(2).
Operation command to indoor unit To 1 .
- 164 -
Normal operation
Error
Unit in the stopped state
Error stop
Error display on the
heat source unit LED
Self-holding of
protection function
Error command to
indoor unit
GB