Heat Defrosting Control; Conditions To Enter Defrosting Mode; Discharge Temperature Protection Control; Outdoor Fan Control - Mitsubishi Electric MSZ-G09SV Service Manual

The LEV opening is corrected according to difference between the target discharge temperature and discharge temperature.
more than Target discharge temperature+11
Target discharge temperature+11 to Target discharge temperature+8
Target discharge temperature+8 to Target discharge temperature+5
Target discharge temperature+5 to Target discharge temperature+2
Target discharge temperature+2 to Target discharge temperature-2
Target discharge temperature-2
Target discharge temperature-5
Target discharge temperature-8
Target discharge temperature-11 or less

9-26. Heat defrosting control

(1) Conditions to enter defrosting mode

1. When temperature of defrosting thermistor is -3: or less.
2.When specified non-defrosting time, is counted in the control P.C. board is satisfied.
(Total time of compressor operating)
Going to defrosting mode at both condition of 1 and 2.
(2) Defrosting operation
1. Compressor stops for 50 seconds, indoor fan is off and defrosting lamp lights.
2. 4-way valve reverses flow, Compressor operates by the frequency in heat defrosting control.
3. After compressor stops for 35 seconds, 4-way valve reverses flow, then defrosting finishes.
(3) Conditions to finish defrosting mode
1. When the defrosting thermistor temperature is 8: or more.
2. When it has spent 10 minutes for defrosting.
Defrosting finishes at condition of 1 or 2.

9-27. Discharge temperature protection control

This protection controls the compressor ON/OFF and operation frequency according to temperature of the discharge
temperature thermistor.
(1) Compressor ON/OFF
When temperature of the discharge temperature thermistor exceeds 116:, the control stops the compressor.
When temperature of the discharge temperature thermistor is 80: or less, the controls starts the compressor.
(2) Compressor operation frequency
When temperature of the discharge temperature thermistor is expected to be higher than 116:, the control decreases
12Hz from the current frequency.
When temperature of the discharge temperature 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 temperature thermistor is expected to be higher than 104: and less than 111:, the
control is set at the current frequency.

9-28. Outdoor fan control

Fan speed is switched according to a number of operating indoor unit and the compressor frequency.
Fan speed
Down
High
Low
Min. Compressor frequency
Note
• When the indoor coil thermistor is 57: or more on HEAT operation, fan speed is fixed to Low.
Or, the indoor coil thermistor is 45: or less on HEAT operation, fan speed is back to normal.
Discharge temperature (:)
to Target discharge temperature-5
to Target discharge temperature-8
to Target discharge temperature-11
Up
Max.
LEV opening
correction (pulse)
COOL
10
4
2
1
0
-1
-2
-5
-8
<Relation between compressor frequency and fan speed>
Mode
Fan speed
Up
COOL
Down
Up
HEAT
Down
62
HEAT
8
2
1
1
0
-1
-1
-2
-6
Indoor unit operation
Single Double
60Hz 60Hz
50Hz 50Hz
60Hz 60Hz
50Hz 50Hz