Outdoor Unit Control - Mitsubishi Electric PKH18FK Technical & Service Manual

3. OUTDOOR UNIT CONTROL

3-1 Outdoor fan control
The rotational frequency of outdoor fan is phase-controlled according to the outdoor coil temperature. This control allows the
cooling operation even with the low outside-air temperature and the heating operation even with the high outside-air tempera-
ture.
3-2 Outdoor unit control
The outdoor unit turns ON/OFF the cooling/heating operation according to orders given from the indoor unit.
3-3 Protective functions
1 If an reversed-phase, an open phase, or an indoor controller abnormality is detected, the outdoor unit will stop operation and
the check mode will start. (For the check mode details, see page 48.)
2 If a protective function works, the compressor will stop running. Three minutes later, the compressor will restart. If the protec-
tive function works again, the compressor will stop running and the check mode will start.
3 The protective function is memorized.
4 The memory is cleared when the POWER ON/OFF button on the remote controller is turned OFF. However, the check mode
display continues until the outdoor unit receives the "operation ON" command from the indoor unit.
3-4 COOL/HEAT operation time chart
Operation starts by
P O W E R b u t t o n ON.
ON
Thermostat
OFF
ON
Compressor
OFF
Crankcase heater
ON
(with jumper wire
OFF
J3)
Crankcase heater
ON
(without jumper
OFF
wire J3)
ON
4-way valve
OFF
( c o o l )
ON
4-way valve
(HEAT)
OFF
ON
Bypass valve
OFF
ON
Outdoor fan
OFF
The room temperature dis-
played on remote controller
becomes equal to set tem-
perature.
60 minutes
60 minutes 60 minutes 60 minutes 60 minutes 60 minutes
10 minutes
3 minutes
w1 If compressor restarts within 10 minuteas, 4-way valve remains ON.
The room temperature dis-
played on remote controller
becomes different from set
temperature.
Operation stops by
POWE R bu tt o n OFF.
60 minutes
Repeats 60-minute
ON/OFF
10 minutes 1
3 minutes
47