Mitsubishi Electric EHST20C-VM6HB Service Manual page 37

Phenomena
3. When pressing the remote controller
operation switch, the OPERATION
display is appeared but it will be
turned off soon.
4. Even controlling by the wireless
remote controller, no beep is heard
and the unit does not start operat-
ing. Operation display is indicated
on wireless remote controller.
5. When operating by the wireless
remote controller, beep sound is
heard, however, unit does not start
operating.
6. Remote controller display works
normally and the unit performs cool-
ing operation, however, the capacity
cannot be fully obtained. (The air
does not cool well.)
7. Remote controller display works
normally and the unit performs
heating operation, however, the
capacity cannot be fully obtained.
8. 1For 3 minutes after temperature
adjuster turns off, the compressor
will not start operating even if tem-
perature adjuster is turned on.
2For 3 minutes after temperature
adjuster turns on, the compressor
will not stop operating even if tem-
perature adjuster is turned off.
(Compressor stops operating
immediately when turning off by
the remote controller.)
OCH533D
Factor
1 After cancelling to select function from the remote
controller, the remote controller operation switch will
be not accepted for approx. 30 seconds.
1The pair number settings of the wireless remote
controller and indoor controller board are mismatched.
1No operation for 2 minutes at most after the power
supply ON.
2Local remote controller operation is prohibited.
• Remote controlling adaptor is connected to CN32
on the indoor controller board.
• Local remote controller operation is prohibited
by centralized controller etc. since it is connected to
MELANS.
3Phenomena of No.2.
1Refrigerant shortage
2Filter clogging
3Heat exchanger clogging
4Air duct short cycle
1Linear expansion valve fault
Opening cannot be adjusted well due to linear
expansion valve fault.
2Refrigerant shortage
3Lack of insulation for refrigerant piping
4Filter clogging
5Heat exchanger clogging
6Air duct short cycle
7Bypass circuit of outdoor unit fault
12Normal operation
(For protection of compressor)
37
Countermeasure
1 Normal operation
1Check the pair number settings.
1Normal operation
2Normal operation
3Check the phenomena No.2.
1• If refrigerant leaks, discharging tempera-
ture rises and LEV opening increases.
Inspect leakage by checking the tem-
perature and opening.
• Check pipe connections for gas leakage.
2Open intake grille and check the filter.
Clean the filter by removing dirt or dust on
it.
3• If the filter is clogged, indoor pipe tem-
perature rises and discharging pressure
increases. Check if heat exchanger is
clogged by inspecting discharging pres-
sure.
• Clean the heat exchanger.
4Remove the blockage.
1• Discharging temperature and indoor heat
exchanger temperature does not rise.
Inspect the failure by checking discharg-
ing pressure.
• Replace linear expansion valve.
2• If refrigerant leaks, discharging tempera
ture rises and LEV opening increases.
Inspect leakage by checking the tem-
perature and opening.
• Check pipe connections for gas leakage.
3Check the insulation.
4Open intake grille and check the filter.
Clean the filter by removing dirt or dust on
it.
5• If the filter is clogged, indoor pipe
temperature rises and discharging
pressure increases. Check if heat
exchanger is clogged by inspecting
discharging pressure.
• Clean the heat exchanger.
6Remove the blockage.
7Check refrigerant system during operation.
12Normal operation