Mitsubishi Heavy Industries SRRM40HENG-L, Handbook, Page: 76 / 1106

74
SRK-H
(7) Dew condensation prevention control for cooling operation
This prevents dew condensation, in the indoor unit, from occurring.
(a) Operating condition: when 52C is kept ON for 30 min. after the unit starts operation.
(b) Operation content: forces the indoor fan to change from Speed 1 to Speed 2.
(c) Resetting condition: When 52C is off, or when dew condensation prevention control has been operating continuously for
30 minutes.
(8) Frost prevention for indoor heat exchanger
[Preventing frost accumulation on the indoor heat exchanger]
During the Cooling or Dry operation in low room air temp. condition, evaporating temperature will decrease and consequently
indoor heat exchanger sometimes gets clogged with frost (or ice).
In order to prevent this trouble, compressor is stopped by under mentioned condition by indoor heat exchanger sensor (Th2) and
timer (built into micro computer circuit) functions.
Also indoor fan is changed over to Lo speed.
CM, FM
O
stoppage condition
1
Temperature of heat exchanger is
0˚C or lower.
2 As least 10 minutes has passed
since the compressor started.
Indoor heat exchanger
temperature (˚C)
CM, FM
O
re-starting condition
1
Temperature of heat exchanger is
7˚C or higher.
2 As least 3 minutes has passed since
the compressor stopped.
Set fan
speed
(9) Microcomputer controlled timely defrosting operation (Heat pump type only)
(a) Defrost Start
Changes in the difference in temperature between the intake air temperature and the indoor heat exchanger temperature
causes frost to build up, at which time defrosting begins. However, defrosting will not occur when the total compressor
operation time or time after defrosting has ended is 40 minutes.
(b) Defrost End (heat exchanger temperature or timer)
1) What the heat exchanger temperature (detected by 23DH) reaches the value given below, defrosting is ended and
heating operation is returned to. Preset values: 14C˚
2) Operation will also return to heating operation when more then 10 minutes has passed since the starting of defrosting
operation.
50
OFF
ON
OFF
ON
OFF
ON
OFF
ON
Indoor
Outdoor
Indoor Fan
Operation Lamp
52 C
(Compressor)
52 X
4
(4 Way Valve)
Outdoor Fan
seconds
1 minute 10 minutes or 23DH OFF 2 minutes
Start Defrosting End Defrosting
Hot
Keep
Hot
Keep
Lit
Flashing
Device operation during defrosting