Mitsubishi Electric Asia Pte Ltd


Frequently Asked Questions

Air Conditioner

What is Fan Coil Unit(FCU)/Indoor Unit?
FCU/Indoor unit is the equipment that is installed inside your house premises such as bedroom,living/dinner room or etc.

What is Condenser Unit(CU)/Outdoor Unit?
CU/Outdoor unit is the equipment that is usually installed outside of your house building.

What is Compressor?
Compressor is only a part that is located inside the Condenser Unit/Outdoor.

The indoor unit is emitting a bad odour
The indoor unit does not produce odour by itself. Generally, the surrounding smell is absorbed into the fan coil unit and discharges out with the air flow.

In many cases, air conditioner blows out bad smelling air because of mold and mildew accumulation at the cooling coil and drain pan. Air circulation resulted in small particles impurities in the air attach themselves to the fins or around drainage areas.
General servicing is required in such cases to eliminate the smell.

The indoor unit is noisy
The line flow fan may have accumulated too much dirt,It is recommended to carry out general servicing.

Poor Cooling
This could be due to insufficient refrigerant or lack of servicing.

If your air conditioner is low on refrigerant, either it was undercharged at installation or it is leaking.If it is leaking, simply adding refrigerant is not a solution. A pressure test to determine the leak should be conducted, fix the leak and then charge the system with the correct amount of refrigerant.

If it’s due to the latter, general cleaning is needed to improve the performance of the air conditioner.

Dew prevention
During COOL or DRY operation with the vane angle at Angle 4 or 5 when the compressor's cumulative operation time exceeds 1 hour, the vane angle automatically changes to Angle 1 for dew prevention. This is not a fault but instead it is a safety feature of the unit.

The fan coil is noisy and the air blown out is weak/irregular
This can be caused by the following:
• The cooling coil may be choked with impurities.
• Dirt had clogged up on the line flow fan after a period of time.
• Filter is dirty.
It is recommended to do general cleaning to improve the performance of the air conditioner. For severe blockages, please engage a professional to perform a thorough cleaning of the unit.

When the fan is set at "Hi/Powerful" fan mode, the indoor unit is noisy
The "Hi/Powerful" fan mode is for rapid cooling and some noise is expected.
It is recommended to reduce the fan speed after the room temperature is achieved to minimize the noise.

The outdoor unit is noisy
It may be due to the following:
• Screws may not be properly tightened.
• No rubber pads were placed underneath the outdoor unit
• Vibration from the refrigerant pipes may be transmitted along the way
• The outdoor unit noisy may increase and vary according to the cooling capacity required.

The indoor unit is too cold
The temperature setting on your remote controller is too low.

The indoor unit cannot be switched on
It may be due to the following:
• The remote controller may be faulty.
• The receiver/infrared ray at the indoor unit may be faulty.
• There is no power supply to the indoor unit.
• The battery of the remote controller needs replacement.
• Please check the power supply source whether there is any trip.

It is recommended to replace any of the above items.

1 out of 4 indoor units are cold without switching ON
• The connecting wires / refrigerant pipes may be connected incorrectly.
• LEV coil/valve may be faulty.

Water is leaking from the indoor unit
This is normally caused by blockage in the drainage pipe. It is recommended to do general servicing for the air conditioner.

Water is leaking from the outdoor unit
This is normal. During cool and dry operations, pipe connecting sections are cooled and causes the moisture from ambient air to condensate. It is recommended to install the recommended drainage kit to prevent water dripping to your neighbour's outdoor unit.

There is some ice formed on the indoor unit.
It may be due to the following:
• The refrigerant gas may be insufficient.
• The air filters, line flow fan or cooling coil may be dirty.

Is there any special filter that can be used against haze?

What is the small piece of white filter found in the indoor unit used for?
It is used to improve air quality.

Is it possible to re-use existing piping?
Yes. Flushing of the existing pipes and vacuuming must be performed.

What is the electrical consumption for air conditioner per day?
It depends on the set temperature, running hours and the electrical tariff charges. Please refer to the NEA website given below for the individual models' annual energy consumption and cost

NEA Website Link

How long should I need to clean or replace the anti-allergy enzyme filter?
It is recommended to clean quarterly. Replacement is required for wear and tear.

How to use “dry” mode of the remote controller?
It is used on a rainy day or when the relative humidity is high. The fan occasionally stops to improve the removal of moisture in the environment.

How do I set the daily timer of the remote controller?
Please refer to the User Manual. The remote controller is of “daily type” setting and is required to program current time first, followed by start and stop button of the timer.

Why does the indoor unit indicator light changes from 2 to 1 light after a certain time?
This shows that the room temperature has reached or close to the remote controller setting temperature.

Can an individual indoor unit be tied to operate only from an individual remote controller?
Yes, please bring your remote controller to us for modification.

Why is there no temperature shown on the remote controller?
The temperature will only be shown in cool mode setting.
The remote controller is faulty. It is recommended to purchase your remote controller with us.

At low speed, it takes a long time to reach remote controller setting temperature
Please switch to “Hi” fan speed for faster cooling.

Is aluminium piping allowed?
No, we do not guarantee on the air conditioning system. It is highly recommended to use copper piping.

There is rust on the outdoor unit.
Rust is not covered under our guarantee terms and conditions. We do not provide paint works for the rust.

Can indoor units be installed in a hair salon?
Due to the compact high efficiency design of the heat exchanger, the use of wall mounted fan coil unit is not recommended. Only ceiling concealed or suspended units are recommended for such installation.

Why are the 2 indicator lights of the fan coil unit blinking?
They are blinking continuously as the safety switch located on the left of the louvers is not properly locked in. It acts as a safety device and does not mean that your unit is faulty. Ensure that the safety switch is properly secured in position and it will stop blinking.


Noise or sound can be heard from the fridge.
It is normal that when the refrigerator is operating, some sound may be produced by the moving mechanical parts such as the below examples:
• Compressor running sound
• System copper piping vibration sound
• Air flow sound from fan motor
• Expansion/contraction sound - When the refrigerator's door is opening, the temperature between ambient and the compartment will cause the structural or the plastics parts to be expansion/contraction thus creating the sound.
• Noise created from Ice marker when producing the ice cubes.
• Refrigerant flowing sound.

Why the refrigerator is not operating?
• Power cord was not plugged.
• Power socket switch is not turn "ON".
• Check whether there is any power failure or circuit breaker tripped.
• Try using the other power socket switch for testing.

The veg compartment is not cold.
•Too much food inside the refrigerator compartment may block the air flow to the vegetable compartment.
•You may increase the air volume by Ref-Temp control (this might affect the Ref-compartment temperature)
•Vegetable compartment door does not properly or the door gasket is loose or has gaps in between. Please replace the door gaskets when it is not in good condition.
•The damper thermostat might be faulty or obstructed by ice formation. You may try carrying out manual de-frosting.

The refrigerator compartment is not cold.
•You may increase the air volume by Ref-Temp control (this might affect the Veg-compartment temperature)
•Refrigerator compartment door does not close properly or the door gasket is loose or has gaps in between. Please replace the door gaskets when it is not in a good condition.
•The damper thermostat might be faulty or obstructed by ice formation. You may try carrying out manual de-frosting.
•Items are placed too close to the air vents resulting in poor cold air circulation. Do not block off any air vents.

There is water dripping inside the refrigerator compartment.
Check whether the Ref-door is closed properly or the door gasket is tight.

Water vapour found at the door gasket surrounding.
•Was the door opened too frequently or the door is ajar.
•Is the unit installed in a high humidity area.
•Are there any gaps found at the gasket.

Water stays at the drain pan behind. Is it normal?
It is normal to have defrosted water collected at the drain pan and they will be evaporated by the heat from the radiator coil/discharge pipe.. It is only abnormal when the water overflows.

The fridge is smelly
•The fridge does not produce smell by itself, it is mostly caused by the food stored at the compartment.
•Contains strong smell food objects using wraps, Tupperware, etc. as to prevent the smell from disseminating into the air-vents

The ice maker is not making ice.
• The ice maker or water pump could be faulty
• No water in the water tank.
• Check water tank is properly in place.
• Ice making function was turned off
• Ensure nothing else other than ice cubes is stored in the ice tray as it may activate the "Ice level" sensor

One fridge door will be opened whenever the other one is closed.
• This happens because refrigerators are built to be air tight. When the fridge door is closed, it pushes the air into the cabinet resulting in the air to enter through the air vent and transfer into other compartment. This will cause the other compartment door to "pop" open. At this time, the bottom door-hinge cater will withhold the door and pull the door close again.
• Refrigerator should be adjusted slightly inclined towards the back.
• Alignment with floor level.

Door cannot close properly
• Ensure door panel or pocket are not obstructed by food parcel or tray itself.
• Too much food obstructing the doors from closing properly.

Why are both sides of the refrigerator cabinet's hot while in operation?
They are anti condensation pipes to prevent condensation building at the cabinet and also for heat dissipation purposes.

What is the required space for a built in refrigerator?
There must be a minimum of 20mm gap on the sides and 100mm gap above the refrigerator.

There are flies in my refrigerator compartment
This may be due to the surrounding environment and can be commonly found when there's a construction site nearby or when the occupancy rate of your block is low.

Alternatively, you may call our service hotline at 6473 0308 to speak to our technical officers for further enquiries.