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Mitsubishi SRK air conditioning support



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 The ZD and HD ranges have been superseded by the Mitsubishi HG & ZG models but the logic is the same.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 heating.

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 completed.

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.

Cooling operation

Outside temperature Approximately 21 to 43 C

Heating operation

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 conditioner.

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 conditioner.

5. Install the air filters and close the air inlet grill. For replacement natural enzyme filters and photocatalytic washable deodorizing filters, contact your dealer.

Tel: +44(0)1234 764128

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