Mitsubishi Electric CMB-PW202V-J, Service Handbook, Page: 101 / 114

[
VIII
Troubleshooting ]
- 92 -
HWE09070 GB
1) WCB: Phenomena when LEV is connected wrongly (reverse connection of LEV1 and LEV3) to the board.
2) Check method of fully open state or fully closed state of LEV
ΠCheck LEV opening (pulse) on the self-diagnosis LED (Outdoor control board SW1).
Full open: 2000 pulses
Fully closed: 110 pulses (In the case of heating-only mode, however, the pulse may become 110 or more.)
ΠWhen LEV is fully open, measure the temperature at the upstream and downstream pipes of LEV, and make sure that there
is no temperature difference.
ΠWhen LEV is fully closed, check that there is no refrigerant flowing sound.
3) Refer to the table below to determine the correct amount of LEV opening, which are controlled by the values of the differential
temperature and of the superheat.
(WCB LEV basic operation characteristic)
Phenomena
Cooling only Cooling main Heating only Heating main
Non-cooling
SC12 small
SC16 small, branch pipe
SC small
WCB sound
Non-cooling and non-heating
SH12 small
SH16 large, but branch pipe
SC small
WCB sound
THM large
Poor heating performance
Indoor heating SC small
THM large
Non-cooling
Indoor heating SC small
THM large
Part
Malfunction
mode
Operation
mode
Content
Standards of judgment on
unit stable operation
WCB
LEV1
Inclined to
close
Cooling
main
Difference between TH11
and TH13 is large.
Cooling main:
5 to 7°C [9 to 12.6°F]
Heating only, Heating
main:
10 to 16°C [18 to 28.8°F]
Heating only
Heating
main
Difference between out-
door unit condensation
temperature and TH14 is
large.
Inclined to
open
Cooling
main
Difference between TH11
and TH13 is small.
Heating only
Heating
main
Difference between out-
door unit condensation
temperature and TH14 is
small.
LEV3
Inclined to
close
Cooling only
Cooling
main
SH12 is large. SH12 < 20°C [36°F]
Heating only
Heating
main
Difference between out-
door unit condensation
temperature and TH14 is
small.
10 to 16°C
[18 to 28.8°F]
Inclined to
open
Cooling only
Cooling
main
SC16 and SH12 are small.
SC16 > 3°C [5.4°F]
SH12 > 3°C [5.4°F]
Heating only
Heating
main
Difference between out-
door unit condensation
temperature and TH14 is
large.
10 to 16°C
[18 to 28.8°F]