Mitsubishi Electric MXZ-18TV Service Manual page 18

11-5.Discharge temperature protection control
This protection controls the compressor ON/OFF and operation frequency according to temperature of the discharge temp.
thermistor.
(1) Compressor ON/OFF
When temperature of the discharge temp. thermistor exceeds 116;, the control stops the compressor.
When temperature of the discharge temp. thermistor is 80; or less, the controls starts the compressor.
(2) Compressor operation frequency
When temperature of the discharge temp. thermistor is expected to be higher than 116;, the control decreases 12Hz from the
current frequency.
When temperature of the discharge temp. thermistor is expected to be higher than 111; and less than 116;, the control
decreases 6Hz from the current frequency.
When temperature of the discharge temp. thermistor is expected to be higher than 104; and less than 111;, the control is set
at the current frequency.
11-6.Refrigerant recovery control on heating
<Control status>
The control performs when the following status are satisfied everything;
• When there is 1 unit or more not operating indoor unit on heat operation. (Excluding thermo OFF)
• When discharge temperature becomes 107; or more.
• When it passed 60 minutes or more since the operation has started or the last refrigerant recovery has controlled.
<Control details>
LEV opening, which adjusts to not operating indoor unit, is considered to be 80 pulse.
<Control finish status>
The control finishes either as follows. However, the LEV opening is considered to be 59 pulse.
• When it passed 60 seconds since the control has started.
• When the discharge temperature is 90; or less.
11-7.Outdoor fan control
Fan speed is switched according to a number of operating indoor unit and the compressor frequency.
Fan speed
Down
Hi
Low
Min. Compressor frequency
Note
• When operation, fan speed of Hi/ Low mode changes to VHi/ Hi mode by promoting those fan speeds respectively by
1 step after defrosting is operated. This control is cleared, when the compressor off.
• When overheat protection of P.C. board temperature or fin temperature operates, the outdoor fan speed is fixed to VHi
mode regardless of compressor frequency. Also, when the overheat protection is cleared, the fan speed is
back to normal
• When the indoor coil thermistor is 57; or more on HEAT operation, fan speed is fixed to Low notch .
Or, the indoor coil thermistor is 45; or less on HEAT operation, fan speed is back to normal.
11-8.Relation between main sensor and actuator
Relation between main sensor and actuator.
Sensor
Discharge temperature thermistor
Indoor pipe temperature thermistor
Defrost thermistor
Evaporation temperature thermistor
Gas pipe temperature thermistor
Fin temperature thermistor
Capacity code
<Relation between compressor frequency and fan speed.>
Up
Max.
Purpose
Protection
Defrosting Protection
Defrosting
Control
Control
Protection
Control
18
Mode
Fan speed
Up
COOL
Down
Up
HEAT
Down
Actuator
Compressor LEV
Indoor unit operation
Single Double
60Hz 60Hz
50Hz 50Hz
60Hz
60Hz
50Hz 50Hz
Outdoor Reversing
fan motor valve