Control Of Ih Energization Without The Compressor In Operation; Capacity Control Between Outdoor Units (When Two Refrigerant Circuits Are Connected); Dehumidification Priority Control - Mitsubishi Electric PUHY-P250YNW-A Service Handbook

[5-2 Outdoor Unit Control ]
5-2-16

Control of IH energization without the compressor in operation

IH is used to heat the compressor motor on the stopped outdoor unit to make liquid refrigerant in the compressor evaporate
or to keep liquid refrigerant from flooding the compressor.
Initial power on after power is turned on: Stays on for 12 hours, and then transitions to the operation that is performed while
the compressor is stopped
When the compressor is stopped: Stays on for 30 minutes after the compressor stopped, and then repeats the on-off cycle
at 30-minute intervals
Lit LED1 on the INV board indicates that the INV board is energized by an IH.
5-2-17 Capacity Control between Outdoor Units (when two refrigerant circuits are
connected)
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
Air conditioning load that is calculated based on the return air temperature is 50% or above.
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.
5-2-18

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 op-
eration.
Under this control, the set temperature will be compulsory at the minimum value.
(Under discharge temperature control:14°C [57°F]. Under suction temperature conrol:19°C [66°F])
The temperature nor the humidity can be controlled simultaneously as the reheat function is not available.
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- chapter 5 BS_05_C