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NOTE 1 :When the outdoor fan is OFF in heating, defrosting of outdoor heat exchanger is not detected by the defrost thermis-
tor RT61.
NOTE 2 :When connected to MXZ-32NV- outdoor unit,the MSH-07/09/12NV-
, MSH-07/09/12/18NV- and
MSH-18NV- indoor unit sends the data for the temperature to the outdoor unit according to the indoor coil temper-
ature.For the further information,refer to the service manual No.OB185.
3. Defrostings
Defrostings of outdoor heat exchanger is controlled by DEICER P.C. board, with detection by the defrost thermistor RT61.
(1) Defrost starting conditions
When all conditions of a) ~ c) are satisfied, the defrosting operation starts.
a) Under the heat operation, the compressor cumulative operation time exceeds 40 minutes without the defrosting opera-
tion working.
b) The defrost thermistor RT61 reads - 3°C or less.
c) After releasing the high pressure protection 4 minutes and 15 seconds have elapsed.
(2) Defrost terminating conditions
When the condition d) or e) is satisfied, the defrosting operation stops.
d) The defrost thermistor RT61 reads 3.1°C or more.
e) The defrosting time exceeds 10 minutes.
E3
E2E1E1
2. High pressure protection
During heating operation, the outdoor fan motor is controlled by the indoor coil thermistor RT12 temperature for excess rise
protection of compressor discharge pressure.
Outdoor fan OFF : 52°C (MSH-07/09/12/24), 50°C (MSH-18)
Outdoor fan ON : 48°C (MSH-07/09/12/24), 46°C (MSH-18)
High pressure protection time chart
Indoor coil thermistor
RT12 temperature
52˚C(MSH-07/09/12/24)
50˚C(MSH-18)
48˚C(MSH-07/09/12/24)
46˚C(MSH-18)
Outdoor fan motor
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON
ON
ON
OFF
OFF
OB207t-2qxp 25/9/97 8:55 PM Page 37