Mitsubishi Electric CMB-WM108V-AA Service Handbook page 128

[ VI Control ]
(2) Heating operation
1. Indoor unit fan operation at
Very Low speed
2. Inverter output 0Hz
3. HBC controller VB3 fully open
4. Solenoid valve OFF
5. Outdoor unit fan stop (PURY)
6. HBC controller solenoid valve control
7. HBC controller LEV control
*Note 1. When the outdoor unit goes into the defrost mode (PURY only), defrost command is sent to the HBC controller and
indoor units.
Upon reception of the command, the indoor units will go into the defrost mode. When defrosting is completed and
upon receiving the signal that indicates the completion of defrosting, indoor units will resume the heating operation.
*Note 2. Defrost end condition: 10 or more minutes must pass after defrost operation.
or Outdoor unit piping temperature : refer to "-7- Defrost operation control" of [2] Controlling HBC Controller
(page 110)
HWE1708A
Heating operation
*Note 1,2
Defrost
operation
NO
4-way valve ON
YES
Test run mode
ON
NO
NO
Thermostat
ON
YES
YES
3-minute restart
prevention
NO
1. Indoor/outdoor unit fan control
2. Inverter frequency control
3. HBC controller VB3 fully open
4. Solenoid valve control
5. HBC controller solenoid valve control
6. HBC controller LEV control
1 3
- 119 -
Normal operation
Defrost operation
Unit in the stopped state
During test run mode
4-way valve OFF
1. Indoor unit fan stop
2. Inverter defrost frequency control
3. HBC controller VB3 fully open
4. Solenoid valve control
5. Outdoor unit fan stop
6. HBC controller solenoid valve control
7. HBC controller LEV control
*Note 1,2
NO
Stopping the
defrost operation
YES
Stopping the defrost operation
GB