Does my Aircon PCB need to be repaired? Common PCB faults

Advances in Air Conditioner design have meant they have considerably increased their efficiency and effectiveness. These advances in design have meant most air conditioners are now computer controlled and contain multiple printed circuit boards (PCB) that carry out control and decision making in the air conditioner.

The PCB's, like any component in your air conditioner, can fail due to both age and external damage. We will go through the most common causes of PCB failure below.

What are the most common causes of Air Conditioner PCB failure?


When vermin get in your air conditioner and onto your printed circuit board, they can cause a short. They do this by bridging across two live elements of the board - usually killing themselves in the process. The most common animal we see in Australia that damages the internal components on a PCB are Gecko's. However, we have also seen snakes, mice, lizards and rats that have damaged PCB components.

External Current Surge

If the external power supply to the air conditioner experiences a surge - that is transmitted to the Air Cons circuit board - then if the voltage is outside the tolerances of the PCB - it will be damaged. Causes of these surges can be lightning strikes, transmission lines being blown together or a number of other issues that have occurred in the electrical distribution network.

Internal Current Surge

There can also be a current surge caused within the air conditioner itself that leads to component failure on the printed circuit board. The most common cause of such a failure is a fan motor. Your air conditioner will have at least two fan motors - one on the indoor unit and one on the outdoor unit - both these units have electronic components which will not tolerate high voltages.

Failed Wiring

Damaged or incorrect wiring within the air conditioner can cause a PCB fault. Usually, this is due to an overvoltage event.

Will I be able to see damage to my PCB?

Your first indication that you have a PCB problem with your air conditioner will that it is not working correctly. It may be dead altogether, it may be showing an error code on your controller or it may just be exhibiting unusual behaviour.

Often when there is a Gecko (or other animals) that has caused a short - they are dead - and in place on the board.

Sometimes the short will leave a visible burn on the PCB - but this is not always the case.

Can I prevent PCB failure?

Typically there is not a lot you can do to prevent PCB board failure.

There are treatments your air conditioning service company can do to reduce the risk of vermin damaging your air conditioner PCB - some of these are permanent, and some are only temporary and need refreshing. None of them can guarantee you won't get vermin damage your PCB.

One thing you can do is make sure your outdoor unit is free from vegetation and dirt - to reduce the risk of ingress of the vermin.

What should I do if I have a PCB failure on my Air Conditioner?

You should not attempt to diagnose or repair your own circuit board. A faulty PCB is something that should only be attended to by a licensed technician. The air conditioner is connected to the electricity supply, and there is a risk of electrocution.

Typically faulty air conditioner PC Boards - like most PC boards - are replaced rather than repaired.

They can be expensive - sometimes multiple $1000's. Some larger air conditioners have multiple boards which need to be replaced at the same time.

There are no generic PCBs - as such, your air conditioning service provider will need to fit a genuine PCB sourced from the system manufacturer.

In rare circumstances, we will attempt to carry out PCB repair. Specialist providers carry out these PCB repairs - unfortunately, they are not always successful. We only go down this path when we are unable to source new replacement boards -as may be the case for systems that have not been in production for some time.

Bottom Line

If you think you have a problem with one of the printed circuit board's in your air conditioner, get in contact with a licensed technician who can accurately diagnose and repair the system.

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