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NOTE: When the outdoor fan is OFF in heating, the defrosting of outdoor heat exchanger is not detected by the defrost ther-
mistor RT61.
3. Defrosting
Defrosting 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 for 40 minutes without the defrosting
operation working.
b) The defrost thermistor RT61 reads 27˚F.
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 38˚F or more.
e) The defrosting time exceeds 10 minutes.
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 : 126˚F (MSH09), 122˚F (MSH12/15/17)
Outdoor fan ON : 118.4˚F (MSH09), 115˚F (MSH12/15/17)
High pressure protection time chart
Indoor coil temperrature thermistor
RT12
126˚F(MSH09)
122˚F(MSH12/15/17)
118˚F(MSH09)
115˚C(MSH12/15/17)
Outdoor fan motor
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON
ON
OFF
OFF
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Summary of Contents for Mr. Slim MSH09NW
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