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Common air conditioner problems FAQ

When the air conditioner starts to have problem, some problems can be easily fixed by the users themselves but some problems require the help of a professional.  Therefore, it is good to find out what is causing the problem first before you consult a professional.  In this post, we try to provide a list of common questions that air conditioner users may encounter when their aircon have problems.  We also try to provide solution to the problem if we think that it is easy for the user to fix the problem without the need to engage a professional.  One of our most useful guide for DIY checking and problem solving come with pictures and video and this can be found in question number 2 below.

FAQ on air conditioner problems for Indoor Unit




1. Why is the air released from the air conditioner outlet not cold ?

Some of the common causes for air conditioner not cold include but are not limited to :

  • Wrong remote control setting – setting temperature too high or not setting temperature to COOL mode.
  • The capacity of the aircon installed is too small for the room.
  • Air conditioner parts (eg filter, fan motor, evaporator coil, etc) are dirty.
  • Air inlet/outlet of FCU or condenser has been blocked by objects.
  • Fan blower is blocked with dust causing cool air to be blocked and can’t be released or blown out.
  • Certain parts in the aircon is faulty.
2. Can you do a DIY check on why your air conditioner is not cold?

Yes you can. Just follow CitiCool’s DIY Aircon Checking Guide.

3. Why the fan coil cannot start when you try to switch it on?

Some common reasons why you can’t switch on the fan coil include:

  • Remote controller is faulty or its battery is weak and need replacement.
  • Fan coil receiver/infrared ray is faulty.
  • Fan coil have no power supply.
  • Power supply trip in the premise.
4. Why the remote control can’t switch on the air conditioner?

This could be due to any of the following problem:

• Printed circuit board of the remote control is faulty.
• Printed circuit board of the fan coil is faulty.
• Fan coil receiver is faulty.
• Broken Wire.

To check whether the problem lies in the remote control or fan coil, test the remote control by using it to switch on other fan coils units.

5. What causes the air conditioner to switch OFF on its own and the indicator light keeps blinking?

When the indicator light keeps blinking, it is a symptom that the aircon is faulty. Therefore, the air conditioner starts to switch off on its own. You are advise to seek a professional aircon technician to troubleshoot on how to resolve the problem.

6. What cause the air conditioner to switch ON and OFF on automatically?

The indoor printed circuit board which controls the operation of the fan coil is faulty already. You will need to replace the printed circuit board.

7.  Is it possible to repair faulty printed circuit board (“PCB”)instead of replacing it with a new one?

Most of the time, it is possible to repair faulty PCB. However, the decision on whether you should repair or replace the PCB depends very much on the cost effectiveness to do so. Normally Citicool will advise client on which part is faulty. We will advise client whether it is more cost effective to do a repair or replacement. Normally, our advice depends on the age and condition of the PCB and the part that is faulty.

8.  Why your remote control doesn’t show the temperature setting?

This is because the remote control only show the temperature when it is set to COOL mode.

9. Why does the fan coil indicator light switches from two to one lighting?

This happens when the room temperature has reached or is closed to temperature setting in the remote control. It could also be due to wrong remote control setting.

10. How to cool the room at a faster speed?

To cool the room at a faster speed, just switch the remote control to a high fan speed for the air conditioner to reach the temperature faster.

11. What causes water to leak from the fan coil?

When installing air conditioner, a drainage pipe build into the fan coil to help carry water from the fan coil to the nearest drain available. Therefore, the drainage pipe helps to transport and discharge water from the fan coil. Once the drainage pipe is accumulated with too much dirt, water will start to build up in the blocked area of the drainage pipe. Since the water can’t be transported away to the drain, soon it will overflow and leak out from the fan coil instead.
When installing air conditioner, it is important to make sure that the running of the drainage pipe from the fan coil to the drain is done with a proper gradient. This is because poor installation of the drainage pipe can result in water leaking problem.

For more information relating to aircon leaking water, refer to the following page:  FAQ on aircon leaking water

12. What causes ice to form on the fan coil unit?

Either there is insufficient refrigerant or the air filters, cooling coil or fan motor are dirty.

13.  What makes the fan coil unit (FCU) to produce a foul smell?

The FCU does not produce any odour on its own. Generally, bad odour is absorbed into the FCU over time and the smell is discharged through the air flowing out from the air outlet.

Usually, the smell comes from mold and mildew that grow on the evaporating coil and drainage pan. As the mold and mildew proliferate especially when there are abundant of moisture, it will discharge foul smell through the air outlet. This is the reason why aircon servicing is required to maintain the cleanliness of the air conditioner system for it to release clean air.

14. What causes the fan coil unit (FCU) to become noisy?

Normally, if the fan coil become noisy, most likely the internal component such as the blower or evaporating coil is dirty and require either general servicing or chemical wash.




FAQ on air conditioner problems for Outdoor Unit




1. What causes water to drip from the condenser?

It is very normal to see water to dripping from the condenser. This happen when the air surrounding the piping condense. (i.e. turning from gaseous form to the liquid form). To prevent the water from dripping onto your neighbour’s outdoor unit, you can install a drainage kit.

2. What causes the condenser (outdoor unit) to become noisy?

There are many factor leading to the outdoor unit becoming noisy.  Some of these include but are not limited to:

  • Loosen parts, loosen wire or screws not properly tightened.
  • Absence of rubber padding beneath the outdoor unit.
  • Leakage of refrigerant or refrigerant valves are damaged or sound from refrigerant pipes vibration.
  • Compressor is worn out or faulty.
3. What causes the condenser to stop operation while the fan coil unit is still operating ?

Once the room temperature reaches the temperature set in the remote controller, the condenser will stop operating. When the temperature in the room rises, the condenser will resume its operation again.

4. When do you need to perform pressure test on an aircon system?

If your aircon always have gas leakages, there is a need to identify the leaking area and seal it up. Pressure test is use to identify the section where the leaking take place. This is done by inducing high pressure into the condenser, fan coil as well as the piping of the refrigerant. Once the location of the leaking is identified, the technician would need to perform repair work to seal the leakage area.




Some articles relating to air conditioner problems

FAQ on AC Condenser noise and repair 

FAQ on aircon leaking water

When does your aircon requires chemical wash?

What you need to know about aircon gas top up?

If you have a question relating to your air conditioner but couldn’t find the answer in the list of FAQ provided above, do feel free to give us a call.

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