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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.
1
Operation explanation and applied data, etc.
(1) PMV control (using two PMV, 1 and 2)
1) PMV (Pulse Motor Valve) is controlled between 90 to
1000 pulses during operation.
2) In cooling operation, PMV opening is controlled
based upon detected TL sensor temp. and detected
Pd pressure value. (Under-Cool control)
3) In heating operation, PMV opening is controlled
based upon detected TS and TD sensor temp. and
detected PS pressure value. (Super-Heat control)
4) Close fully PMV opening when thermostat is OFF,
operation stops and A.C. stops in trouble.
Remarks
• In heating operation,
PMV2 is 0 pulses and
PMV may be controlled by
PMV1 only with the
minimum 45 pulses.
Item
Pulse Motor Valve
(PMV) control
2 Outdoor fan control (1) Cooling fan control
1) Outdoor fan speed (mode) is controlled based upon
detected Pd pressure value.
2) In a specified time when cooling operation started,
the center outdoor unit controls the outdoor fan
speed based upon detected Pd pressure value.
The follower outdoor unit controls the outdoor fan
speed (mode) based upon detected TE sensor temp.
(2) Heating fan control
1) Outdoor fan speed (mode) is controlled based upon
detected TE sensor temp.
2) If TE > 25°C has been continuously detected for 5
minutes, the operation may stop. In this case, the
status is same as one in usual thermostat-OFF, so
the operation restarts.
3) After A.C started, this control is not performed during
the specified time after defrost operation and defrost
control.
4) When refrigerant is excessively shortened, START/
STOP operation may be repeated by this control.
(3) Control for follower unit stop
The fan is driven with lower limit mode to prevent
refrigerant accumulation into the outdoor heat ex-
changer.
PMV opening
45
90
500
550
1000
Min. Med. Max.
PMV 1
PMV 2
When TE temp. (ambient
temperature) exceeds 25°C,
Heating operation stops.
(Over the operation temp.
condition of ambient temp.)
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