Mitsubishi SRK air conditioning
systems fault diagnosis procedure as listed below. The ZD and HD ranges have
been superseded by the Mitsubishi HG & ZG models but the logic is the same.
Characteristics of HEAT mode operation
Mechanism and capacity of HEAT mode operation
• The unit draws in heat from the cold outside air, transfers it
indoors and heats the room. The heating capacity of the heat pump mechanism
decreases when the outside air temperature gets colder.
• The hot air circulation system takes a while before warming up
the room temperature.
• If the outside temperature becomes extremely low, it would be
better to use an additional source of heating.
If the outside temperature becomes low and humidity is high, the
heat exchanger in the outdoor unit may frost over, which prevents efficient
If this happens, the automatic defroster is activated and during
defrosting the heating operation stops for 5 to 10 minutes.
• Both indoor and outdoor fans stop and the RUN light (green)
blinks slowly (1.5 sec. ON, 0.5 sec. OFF) during defrosting.
• The outdoor unit may give off some steam during defrosting.
This is to help the defrosting process and is not a defect.
• The HEAT operation resumes as soon as defrosting has been
Air conditioner operating conditions
Use within the following operational range. Operating
outside of this range may result in the protection devices being activated,
preventing the unit from working.
Outside temperature Approximately 21 to 43 °C
Below approximately -15 to 21 °C
Below approximately 80%
The long-term use of the unit with a humidity level Inside
humidity exceeding 80% may result in condensation forming on the — surface of
the indoor unit, leading to water drips.
Dependent upon service conditions and operating environment,
the inside of the air conditioner may become dirty after a number of seasons'
service (3 to 5 years). This will reduce performance. In
addition to normal cleaning, we would recommend inspection and maintenance. (The
air conditioner has a longer life without any trouble.)
• Contact your dealer, or any distributor, for inspection and
maintenance. (There will be a charge for this service).
• We would recommend inspection and maintenance to be carried
out during the off-season.
• If the supply cord of this appliance is damaged, it must only
be replaced by a repair shop appointed by the manufacturer, because special
purpose tools are required.
Inspecting and replacing the natural enzyme filter and the
photocatalytic washable deodorizing filter
1. Open the air inlet grill and remove the air filters.
2. Remove the filter holders, with the natural enzyme filter and
the photocatalytic washable
deodorizing filter installed in the holders, from the air
3. Remove the natural enzyme filter from the filter holder and
inspect the filter. Use a vacuum cleaner to remove any dust or dirt from the natural enzyme
filter. Replace the natural enzyme filter if it cannot be cleaned or if it has been used for about
1 year. (The natural enzyme filter should be replaced after about 1 year
of use. However, the actual replacement period may vary depending on the conditions in which
the filter is used.) Remove the photocatalytic washable deodorizing filter from the
filter holder and inspect the filter. Periodically, remove any dust or dirt from the
photocatalytic washable deodorizing filter. If the photocatalytic washable deodorizing filter is
particularly dirty, it may be washed with water. However, the filter is fragile so be sure to wash it
installed in the filter holder to avoid damaging it. After washing the filter, place it in
sunlight to dry. Placing the filter in sunlight revitalizes the deodorizing effect. (Do not dispose of the filter holders. They are reused.)
4. Install the natural enzyme filter and the photocatalytic
washable deodorizing filter in the filter holders, and then install the filter holders in the air
5. Install the air filters and close the air inlet grill. For replacement natural enzyme filters and photocatalytic
washable deodorizing filters, contact your dealer.