Mitsubishi Electric PQRY-P200YEM-A Service Handbook page 56

(3) Heating operation
1. Indoor unit fan very low speed
operations
2. Inverter output 0Hz
3. Indoor unit LEV
4. Solenoid valve OFF
5. Outdoor unit fan stop
6. BC controller solenoid valve
OFF (PURY)
7. BC controller LEV fully closed
(PURY)
8. 52C off
Note : 1 When outdoor unit starts defrosting, it transmits defrost operations command to (BC controller and) indoor unit, and the
indoor unit starts defrosting operations.
Similarly when defrosting operation stops, indoor unit returns to heating operation after receiving defrost end command of
outdoor unit.
Heating operation
Note : 1
Defrosting
operation
NO
4-way valve ON
Test run start
NO
NO
Thermostat ON
YES
YES 3-minute
restart
prevention
NO
1. Indoor and outdoor unit fan
control
2. Inverter frequency control
3. Indoor unit LEV
4. Solenoid valve control
5. BC controller solenoid valve
control (PURY)
6. BC controller LEV control
(PURY)
7. 52C control
–55–
Normal operations
Defrosting operations
Stop
Test run
YES
YES
1. Indoor unit fan stop
2. Inverter defrost frequency control
3. Indoor unit LEV fully opened
4. Solenoid valve control
5. Outdoor unit fan stop
6. BC controller solenoid valve control
(PURY)
7. BC controller LEV control (PUR
8. 52C control
4-way valve OFF
Y)