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2-1. Control Functions
Electronic control valve control
Opening of the electronic control valve is controlled
so that the appropriate operating conditions are main-
tained, based on the signal from each sensor (dis-
charge temperature [TD], intake temperature [TS],
outdoor heat exchanger temperature [C1], and indoor
heat exchanger temperature [E1, E2]).
Discharge temperature release control
(1) This control lowers the operating frequency of the
compressor when electronic control valve control
is unable to maintain the appropriate operating
conditions because the discharge temperature
fails to decline or because there is a sudden
increase in the discharge temperature.
(2) If the discharge temperature exceeds 111°C, the
compressor is stopped and then restarted. (Error
count = 1)
(3) The error count is cleared when operation has
continued for 10 minutes after the compressor
was restarted.
(4) If (2) repeats 4 times without the error count being
cleared (error count = 4), alarm “P03” occurs.
Current release control
The compressor operating frequency is controlled so
that the current that is input to the inverter compressor
does not exceed the designated value (control value).
Outdoor unit fan control
1. Cooling fan control
(1) The outdoor unit fan minimum speed and maxi-
mum speed are determined according to the out-
door air temperature and the operating frequency.
The speed is controlled in stages between the
minimum speed and maximum speed, based on
the outdoor heat exchanger temperature (C2) at
that time.
(2) For 60 seconds after start, the outdoor unit fan
operates at maximum speed, as determined by
the outdoor air temperature and operating fre-
quency at that time.
Subsequently, the fan operates at low speed until
the outdoor heat exchanger temperature (C2) rises.
(3) If the discharge temperature (TD) sensor is abnor-
mal or has become disconnected, the fan will not
operate and a protective device is activated.
2. Heating fan control
(1) The outdoor unit fan minimum speed and maxi-
mum speed are determined according to the out-
door air temperature and operating frequency. The
speed is controlled in stages between the minimum
speed and maximum speed, based on the outdoor
heat exchanger temperature (C1) at that time.
(2) If the outdoor heat exchanger temperature (C2) is
24°C or higher continuously for 5 minutes, fan
operation may stop (same conditions as when the
thermostat is OFF). In this case, the fan will
restart after 3 minutes.
(3) This control is not performed during the 3 minutes
after start, for 1 minute after defrost ends, and
while defrost is in progress.
Coil heating control
(1) This control applies current to the coil of the
stopped compressor to heat the compressor in
place of the crank case heater.
(2) When the discharge temperature (TD) is less
than 25°C, the current application judgment is
made based on the outdoor air temperature (TO).
• Current application starts when the outdoor air
temperature drops to 15°C or below.
• Current application stops when the outdoor air
temperature rises above 18°C.
Control for prevention of short intermittent
operation
In order to protect the compressor, this control does
not allow the compressor to be stopped for 10 min-
utes after operation starts, even if the thermostat OFF
signal is received from the indoor unit.
Control for prevention of high cooling loads
(1) This control reduces abnormal high-pressure
increases during cooling operation.
(2) If the outdoor heat exchanger temperature (C2)
reaches 64°C or above, the compressor is
stopped. (Error count = 1)
(3) 3 minutes after the compressor stops, if the out-
door heat exchanger temperature (C2) is less
than 55°C the compressor is restarted. If opera-
tion subsequently continues for 10 minutes, the
error count is cleared.
(4) If the outdoor heat exchanger temperature (C2)
again reaches 64°C or higher within 10 minutes
after the compressor restarts, the compressor is
stopped again. (Error count = 2)
(5) If the above start/stop of the compressor is repeat-
ed 10 times (error count = 10), alarm “P20” occurs.
At this time, operation stops and does not restart.
(6) If the compressor has stopped because the out-
door heat exchanger temperature (C2) reached
64°C or higher, and the temperature remains at
64°C or higher for 30 seconds, alarm “P20”
occurs even when the error count is less than 10.
At this time, operation stops and does not restart.
(7) For 30 minutes or longer after the compressor
restarts, the control value for “current release
control” is reduced to 70 – 90%.
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