Capacity Control Between Outdoor Units; Dehumidification Priority Control; Operation Mode - Mitsubishi Electric PU(H)Y-P250YGM-A Service Handbook

-11- Capacity Control between Outdoor Units (when two refrigerant circuits are connect-
ed)
The following two capacity control methods between indoor units are available.
Control to make only one of the outdoor units (which has the smaller address) operate and keep running during low-load
hours at startup.
Control to make one of the outdoor units stop, and the other outdoor unit operate when the load becomes low during
normal operation. After a certain period of time has passed since only one of the outdoor units started operation, the unit
in operation stops, and the other outdoor unit starts operation automatically.
(1) Starting Conditions
When it is determined that the load is less than 50%, using suction temperature as a reference.
Operation frequencies of both indoor and outdoor units remain near the minimum level three minutes after start-up.
(2) Stopping Conditions
When operation frequency of the running unit rises up near the maximum capacity.
When it is determined that the load is over 50%, using suction temperature as a reference.
When compressor stops while running only one unit.

-12- Dehumidification priority control

The dehumidification priority control is the control to increase the amount of dehumidification by increasing the frequency
of the compressor when the external signal (dehumidification command) is received during cooling operation.
During dehumidification priority control, the room temperature may drop below the preset temperature set during normal
operation.
Under this control, the set temperature wil be compulsory at the minimum value.
(Under discharge temperature control:14°C Under suction temperature conrol:19°C)
The temperature nor the humidity can be controlled simultaneously as the reheat function is not available.

-13- Operation Mode

(1) Indoor unit operation mode
The operation mode can be selected from the following 4 modes using the remote controller.
1 Cooling mode
2 Heating mode
3 Fan mode
4 Stopping mode
(2) Outdoor unit operation mode
1 Cooling mode
2 Heating mode
3 Stopping mode
Note:
The heating mode can be used for standby of the indoor unit when the outdoor temperature is low. Confirm that the de-
vices to be cooled are not influenced by the heat.
The discharge temperature control cannot be used.
The discharge temperature is controlled not to drop less or equal 30°C. It may take time to reach the indoor target tem-
perature.
When the indoor temperature reaches the cooling operation range, switch the operation from heating to cooling.
All indoor units in operation are in cooling mode.
All indoor units in operation are in heating mode.
All indoor units are in fan mode or stopping mode.
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