Mitsubishi Heavy Industries SRK20ZIX-S Service Manual page 45

(13) Serial signal transmission error protection
(a) Purpose: Prevents malfunction resulting from error on the indoor ↔ outdoor signals.
(b) Detail of operation: If the compressor is operating and a serial signal cannot be received from the indoor control with
(14) Rotor lock
If the motor for the compressor does not turn after it has been started, it is determined that a compressor lock has occurred and
the compressor is stopped.
(15) Outdoor fan motor protection
If the outdoor fan motor has operated at  rpm or under for more than 0 seconds, the compressor and fan motor are stopped.
(16) Outdoor fan control at low outdoor temperature
Cooling
◆
(a) Operating conditions: When the outdoor air temperature (TH) is ºC or lower continues for 0 seconds while the
(b) Detail of operation: After the outdoor fan operates at A speed for 0 seconds; the corresponding outdoor heat
Outdoor heat exchanger temperature = < ºC
)
After the outdoor fan speed drops (down) to  speed for 0 seconds; if the outdoor heat exchanger temperature is
lower than ºC, gradually reduce the outdoor fan speed by 1 speed. (Lower limit 1st speed)
ºC < Outdoor heat exchanger temperature = < ºC
)
After the outdoor fan speed maintains at A speed for 0 seconds; if the outdoor heat exchanger temperature is ºC~
ºC, maintain outdoor fan speed.
) Outdoor heat exchanger tempeature > ºC
After the outdoor fan speed rises (up) to  speed for 0 seconds; if the outdoor heat exchanger temperature is higher
than ºC, gradually increase outdoor fan speed by  speed. (Upper limit rd speed)
(c) Reset conditions: When either of the following conditions is satisfied
) The outdoor air temperature (TH) is ºC or higher.
) The compressor command speed is 0 rps.
Heating
◆
(a) Operating conditions: When the outdoor air temperature (TH) is ºC or lower continues for 0 seconds while the
(b) Detail of operation: The outdoor fan is stepped up by  speed step at each 0 seconds. (Upper limit th speed)
(c) Reset conditions: When either of the following conditions is satisfied
) The outdoor air temperature (TH) is ºC or higher.
) The compressor command speed is 0 rps.
outdoor control having serial signals continues for  minute and  seconds, the compressor is
stopped.
After the compressor has been stopped, it will be restarted after the compressor start delay if a serial
signal can be received again from the indoor control.
compressor command speed is other than 0 rps.
exchanger temperature shall implement the following controls.
¡ Value of A
Outdoor temperature > 10˚C
Outdoor temperature < = 10˚C
compressor command speed is other than 0 rps.
Outdoor fan
nd speed
st speed

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