Mitsubishi Electric PUHY-P72THMU-A Service Handbook page 120

[ VII Control ]
(2) Heating operation
1. Indoor unit fan operation at
Very Low speed
2. Inverter output 0Hz
3. Indoor unit LEV, LEV1 Fully closed
LEV2a, LEV2b rated opening
4. All solenoid valves OFF
5. Outdoor unit fan stop
6. 72C OFF
1) When outdoor unit starts defrosting, it transmits defrost operations command to indoor unit, and the indoor unit start defrosting
operations. Similarly when defrosting operation stops, indoor unit returns to heating operation after receiving defrost end com-
mand of outdoor unit.
2) Defrost end condition: 12 or more minutes must pass after defrost operation or outdoor unit piping temperature.
Refer to "-7-. Defrost operation control" of [2] Controlling the Outdoor Unit for the temperature.
HWE08040
Heating operation
*Note 1,2
YES
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. Indoor unit LEV, LEV1,LEV2a, LEV2b control
4. Solenoid valve control
5. 72C control
- 111 -
Normal operation
Defrost operation
Unit in the stopped state
During test run mode
4-way valve OFF
1. Indoor unit fan stops
2. Inverter defrost frequency control
3. Indoor unit LEV fully closed.
4. Solenoid valve control
5. Outdoor unit fan stop
6. LEV1 control
7. LEV2a, LEV2b fully opened.
8. 72C control
*Note 1,2
NO
Stopping the
defrost operation
YES
Stopping the defrost
operation
Return to heating
operation
GB