Operation Start/Operation End - Toshiba MiNi-SMMS MCY-MAP0501HT Service Manual

6-2. Outdoor Unit

6-2-1. Operation Start/Operation End

The compressor, solenoid valve, pulse motor valve (PMV), outdoor fan, etc. are controlled by a command from
the indoor controller. The follower outdoor unit starts/stops by a command from the header outdoor unit.
No. Item
1 Pulse Motor Valve
(PMV) control
2 Outdoor fan
control
3 Capacity control
4 Refrigerant/Oil
recovery control
Operation explanation and applied data, etc.
(1) PMV control
• Each PMV is controlled between 45 to 500 pulses during
operation.
• In cooling operation, PMV opening is dependent upon
detected readings from the TL sensor and Pd pressure
sensor (sub-cool control).
• In heating operation, PMV opening is dependent upon
detected readings from the TS and TD sensors and the Ps
pressure sensor (super-heat control).
• Each PMV will be fully closed when the system is in
'Standby' or 'No demand' modes and when a malfunction in
the system has occurred.
(1) Fan control in all cooling operation
1) The outdoor fan speed/mode is determined by the
detected Pd pressure value.
2) When cooling operation has started, the outdoor fan
speed of the master unit is controlled using the detected
Pd pressure value.
(2) Fan control in all heating operation
1) The outdoor fan speed/mode is determined by the
detected TE sensor value.
2) If a TE value > 25°C has been continuously detected for 5
minutes, the operation may stop.
3) After start up, this control is not available during the
specified time after a defrost operation.
4) This operation may start and stop repeatedly when the
system is undercharged.
(3) Fan control for mainly cooling, part heating operation
The outdoor fan speed (mode) is controlled according to the
target of the Pd (Discharge pressure).
(1) The capacity request command received from the indoor
controller determines the inverter frequency control of the
outdoor unit.
(1) During cooling operation, this function is executed to
regularly to recover the refrigerant/oil from the indoor units
and connecting pipe-work back to the outdoor unit.
This function is also performed to prevent stagnated refriger-
ant accumulating in the outdoor heat exchanger during low
ambient cooling.
1) Control conditions
• Cooling oil recovery operation is executed approximately
every 3 hours.
2) Contents of control
• The recovery period lasts for approximately 2 or 3 minutes
though this is dependant on the system capacity.
(2) Refrigerant recovery control in heating room
This function is executed regularly to recover the liquid
refrigerant from the indoor unit.
It is also used to recover oil present in the outdoor heat
exchanger during the heating overload operation
(except during defrost operation).
1) Heating operation oil, recovery control is executed
approximately every hour.
2) The period of recovery lasts for approximately 2 to 10
minutes though this is dependent upon the load condition.
59
Remarks
When TE temp. (ambient
temperature) exceeds
25°C, Heating operation
stops.
• The maximum fan
speed differs depend-
ing on the outdoor HP.
• Min. frequency: 26Hz
• Control for refrigerant/
oil recovery is per-
formed approximately
every 3 hours.
• Recovery lasts for
approximately 2 or 3
minutes though this is
dependent upon the
system capacity.