Outline Of Cooling Operation - Mitsubishi Heavy Industries SRF25ZS-W Service Manual

5) During continuous compressor operation
In addition, when the speed command from the indoor control of the indoor unit during heating operation has counted 0
rps 10 times or more and all conditions of 1), 2) and 3) above and the outdoor air temperature is 3°C or less are satisfied
(note that when the temperature for outdoor heat exchanger temperature sensor (TH1) is -5°C or less: 62 rps or more,
-4°C or less: less than 62 rps), defrost operation is started.
(ii) Ending conditions (Operation returns to the heating cycle when either one of the following is satisfied.)
1) Outdoor heat exchanger temperature sensor (TH1) : 13ºC (SRF50 : 10°C) or higher
2) Continued time of defrost operation → For more than 15 minutes
¡Defrost operation
Heating operation
Depends on an operation condition, the time can be longer than 7 minutes.

(14) Outline of cooling operation

(a) Operation of major functional components in cooling mode
Compressor
Indoor fan motor
Outdoor fan motor
4-way valve
(b) Detail of control in each mode (Pattern)
(i) Fuzzy operation
During the fuzzy operation, the air flow and the compressor speed are controlled by calculating the difference between
the room temperature setting correction temperature and the return air temperature.
Model
Fan speed
Auto
HI
MED
LO
ULO
Model SRF50
SRF50
0
-5
-10
-15
-20
-20 -15 -10
Outdoor air temperature (℃)
Max. 15 minutes
Cooling
Thermostat ON Thermostat OFF
ON
ON
ON
(few minutes ON)
OFF
SRF25ZS-W SRF35ZS-W
15 - 72rps 15 - 104rps
15 - 72rps 15 - 104rps
15 - 48rps 15 - 71rps
15 - 40rps 15 - 58rps
15 - 34rps 15 - 46rps
-
Defrost operation
start
-5 0 5 10
2-7 minutes
Hot keep operation
Failure
OFF OFF
ON OFF
OFF OFF
(few minutes ON)
OFF OFF
SRF50ZSX-W
12 - 86rps
12 - 86rps
12 - 58rps
12 - 48rps
12 - 38rps
8
-
'20 • SRF-SM-311