Mitsubishi Electric MXZ-8B48NA Technical & Service Manual page 50

9-4. TROUBLESHOOTING BY INFERIOR PHENOMENA
Phenomena
1. 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.)
2. Remote controller display works
normally and the unit performs
heating operation, however, the
capacity cannot be fully obtained.
3.1For 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.)
Factor
1Refrigerant shortage
2Filter clogging
3Heat exchanger clogging
4Air duct short cycle
1Linear expansion valve fault
Opening cannot be adjusted well due to linear expan-
sion 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)
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.
2 Open 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.
4 Remove 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.
3 Check the insulation.
4 Open intake grille and check the filter.
Clean the filter by removing dirt or dust
on it.
5 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.
6 Remove the blockage.
7 Check refrigerant system during opera-
tion.
12Normal operation
50
Countermeasure