A Beginner’s Guide to Aircon Printed Circuit Boards

Is your air conditioner not working as it should? It might be because of the printed circuit board (PCB) inside it. This article will guide you through understanding an AC PCB, why it’s important, and how to fix or replace one if needed.

Let’s dive in!

Understanding Aircon Printed Circuit Boards (PCBs)

Aircon Printed Circuit Boards (PCBs) are the brains behind your air conditioning unit’s operations. They manage everything from temperature regulation to ensuring the system runs efficiently.

Definition of AC PCB

An AC Printed Circuit Board (PCB) serves as the backbone for managing the operations within an air conditioning system. Much like a computer’s motherboard, this green board with wires organises electronic components such as resistors, capacitors, and transistors in a precise layout to perform its functions efficiently.

It is crafted from non-conductive materials like fibreglass or composite epoxy, offering a stable base that supports various electronic devices crucial for air conditioner operation.

The role of an AC PCB extends beyond mere organisation; it dictates how the air conditioning unit responds to commands and controls temperature settings. Integrating sensor signals and executing commands based on these inputs ensures your environment remains comfortable without energy wastage.

Its ability to manage electrical currents and signal integrity makes it indispensable in achieving effective climate control through dehumidification, cooling fan regulation, and compressor management.

The function of AC PCB

The AC PCB is crucial in managing and executing commands within the air conditioning unit. It uses microcontrollers and capacitors to control various processes, such as adjusting temperature levels, regulating fan speed, and ensuring efficient operation of compressors.

This ensures that the room maintains a comfortable temperature while also conserving energy.

Moreover, it oversees safety checks by monitoring voltage fluctuations and preventing short circuits. The circuit board communicates with different components like evaporator, condenser, and motors to keep everything running smoothly.

Its ability to swiftly process data helps maintain the aircon system’s optimal performance without manual intervention.

Types of AC PCB

Air conditioning systems utilise different AC PCBs to meet diverse operational needs. Rigid PCBs, known for their sturdy structure, are commonly found in standard air conditioners due to their durability and reliability.

These boards support a variety of electronic components like resistors, capacitors, and integrated circuits that help manage the functionality of the aircon units.

Another variant is the flexible PCBs or flex PCBS, which offer versatility and can bend to fit into compact spaces within split air conditioners or portable units. Their adaptability makes them ideal for complex circuitry configurations needed in modern HVAC systems, and they have advanced features such as Bluetooth connectivity and Wi-Fi integration for smart temperature control.

The Importance of AC PCB in Air Conditioners

The AC PCB plays a pivotal role in managing the smooth operation of air conditioners. It ensures that all components work harmoniously, leading to efficient cooling and heating.

Control of Air Conditioner Processes

Air conditioner printed circuit boards (PCBs) play a critical role in managing the operations of air conditioning units. They send commands to various components, ensuring that processes such as compressor on/off, temperature adjustment, and dehumidifying functions operate smoothly.

PCBs facilitate this seamless communication by utilising microchips and relays embedded within their design.

These boards also regulate the power supply to different aircon parts, including the motor running capacitor and expansion valve. This ensures optimal performance while maintaining energy efficiency.

Carefully monitoring room temperature sensors and thermostats allows AC PCBs to adapt the air conditioner’s functionality to provide a comfortable environment without manual intervention.

Performance of Safety Checks

Engineers perform safety checks on the air conditioner’s printed circuit board (PCB) to ensure it functions correctly and safely. These inspections are vital for identifying issues that might not be immediately obvious but could lead to bigger problems if ignored.

They examine solder joints, wiring, and components like capacitors and resistors for signs of wear or damage. Proper communication between various parts of the unit is paramount.

Testing also involves checking the PCB against electrical failures, such as short circuits or overloads that might result in unsafe operation. These evaluations help determine whether a faulty PCB needs repair or replacement, maintaining the air conditioner’s efficiency and safety.

Utilising tools like automated optical inspection systems and multimeters, technicians assess heat dissipation levels and look for any abnormalities in power supply units to prevent electrostatic discharge from damaging sensitive parts.

How AC PCB Works

An air conditioning unit’s PCB acts as its brain, receiving commands and managing data communication across the system. It directly controls capacitors, engaging them to adjust the aircon’s power supply.

This intricate process begins with a user setting temperatures or modes via the remote control. The signal travels to the PCB, which interprets this information and orchestrates other components like valves and transformers to achieve the desired climate.

Components on the PCB work harmoniously, ensuring the aircon unit’s smooth operation. They monitor temperature changes and command the switching of modes to maintain comfort levels.

Active elements such as transistors switch circuits on or off based on instructions from the PCB, regulating electricity flow through various parts of an AC system. This coordination is crucial for efficient energy use and maintaining optimal performance of air conditioning units without manual intervention.

Common Issues with AC PCB

Air conditioner printed circuit boards often face problems that disrupt their normal operation, making it vital to understand these challenges for effective troubleshooting.

Inconsistent Settings and Commands

One common issue with aircon printed circuit boards (PCBs) involves inconsistent settings and commands. The AC PCB is crucial for relaying precise instructions to the air conditioner’s components, such as adjusting temperatures or switching modes.

However, if the PCB suffers from faults due to design flaws or errors in PCB assembly, it may send incorrect signals. This leads to situations where the air conditioning unit does not respond accurately to user inputs.

Users might find their attempts to change settings unfruitful, experiencing frustration when the temperature remains constant despite adjusting the controls. Similarly, trying to switch between different modes may result in no change at all.

These symptoms indicate a malfunctioning circuit board that requires immediate troubleshooting and potential rework station intervention for repairs or replacement. Quick action ensures optimal performance and prolongs the life of both the PCB and air conditioner unit.

Air Conditioner Fails to Power On

A notable problem with air conditioners is the failure to power on, often traced back to issues with the AC PCB. Improper input voltage during installation can damage the PCB, rendering the air conditioner unresponsive.

This critical component controls start capacitors and ensures smooth heat transmission, a process integral to the operation. An incorrect setup may lead to irreversible damage.

Damage or incorrect wiring within the unit also plays a significant role in PCB faults, frequently due to overvoltage events. These mishaps can corrode vital connections or cause short circuits in surface mount components.

Each incident interrupts the normal function of printed circuit board assembly, preventing the aircon from starting as expected. Regular maintenance checks help identify these problems early, preventing costly replacements and ensuring continuous operation.

Detecting a Faulty AC PCB

Detecting a faulty AC PCB is crucial for maintaining the optimal performance of your aircon. Here are several steps to identify a malfunctioning control board:

  1. Observe erratic system behaviour, such as incorrect temperature readings or frequent cycling. These signs indicate the AC’s PCB may not be functioning correctly.
  2. Look for visible damage on the PCB, such as burn marks or corroded components. Visual inspection can quickly reveal issues with the board.
  3. Check for a complete system failure. If the air conditioner fails to power, it could be due to a faulty AC PCB.
  4. Listen for unusual noises coming from the aircon unit. Strange sounds can signal that the PCB struggles to manage the system effectively.
  5. Measure improper input voltage at installation points. The voltage that doesn’t match the recommended levels can damage the PCB over time.
  6. Compare current system performance with previous operation levels. A sudden drop in efficiency might stem from PCB problems.
  7. Use a multimeter to test for short circuits on the PCB, as these are common causes of faults within the board.
  8. Assess whether the aircon displays inconsistent settings or commands, which can point towards a malfunctioning circuit board.

Causes of AC PCB Failure

Aircon Printed Circuit Boards (PCBs) are crucial for efficiently operating air conditioners. However, several factors can lead to their failure.

  1. Dust and moisture exposure is a common cause of PCB damage. These elements can corrode metal components and disrupt the circuit paths.
  2. Accidents like dropping can instantly damage the delicate parts of the PCB, causing it to fail.
  3. Manufacturing defects during assembly might leave the PCB susceptible to early failure. Issues can arise from incorrect soldering or placement of components.
  4. Solder joints become overly conductive if too much moisture seeps into the solder, leading to short circuits.
  5. The use of poorly manufactured components compromises the overall stability and performance of the PCB.
  6. Plating voids create gaps in connectivity, disrupting electrical flow and causing malfunctions.
  7. Insufficient copper-to-edge clearance may lead to short circuits as edges touch, disrupting the function of critical components on the PCB.
  8. High temperatures from improper cooling or overuse can lead to thermal stress, warping PCBs and damaging their structural integrity.
  9. Electrical surges such as lightning strikes or power spikes can overwhelm and burn out sensitive electronic components on the board.
  10. Wear and tear over time naturally degrades connections and components, leading to eventual failure without proper maintenance.

How to Repair AC PCB

Repairing an AC PCB is possible and often a cost-effective decision. This approach can save money and extend the air conditioner’s life, especially if the replacement cost is high due to the year and model of the unit. Here’s how to repair an AC PCB:

  1. Identify the Issue: First, diagnose what’s wrong with your PCB. Use diagnostic tools or visual inspection to spot burned areas or damaged components.
  2. Gather Your Tools: Prepare scissors, a sharp knife, sandpaper, and alcohol-dipped cotton swabs. These will help clean and prepare the board for repairs.
  3. Turn Off Power: Ensure safety by turning off power to your air conditioner. This prevents any electrical accidents during the repair process.
  4. Remove the PCB: Carefully remove the printed circuit board from your air conditioner. Handle it gently to avoid further damage.
  5. Clean the Board: Use alcohol-dipped cotton swabs to clean any dirt or residue on the PCB. Sandpaper can help smooth out rough spots carefully.
  6. Desolder Broken Components: Apply a soldering iron to remove damaged components from the board. Do this step with patience and precision.
  7. Replace Components: Solder new components onto the PCB where old ones were removed. Ensure you have compatible parts that match the original specifications.
  8. Check Connections: Inspect all soldered connections for solidity and accuracy. Use a magnifying glass if needed to ensure there are no short circuits.
  9. Test Run: Before re-installing, conduct a test run of the repaired PCB outside of the unit, if possible, to verify functionality.
  10. Reinstall PCB: Once satisfied with repairs, place the PCB back into your air conditioner, carefully aligning it correctly.
  11. Power On Test: Finally, restore power to your air conditioner and test if it operates as expected after repairs.

Replacement Costs for a Faulty Control Board

Replacement costs for a faulty aircon control board vary greatly depending on the unit type and whether you opt for a new or refurbished part. Below is a detailed breakdown presented in HTML Table format:

Type of Replacement Cost Range
General Faulty Air Conditioning Control Board $100 to $700
Aircon Indoor Unit Control Board $350 to $450
Condenser Unit Control Board $480 to $600
Refurbished Aircon Control Board $180 to $250
Residential Condenser Units $200 to $600

This table summarises the cost implications of replacing a faulty aircon printed circuit board. Options include both brand-new and refurbished parts, catering to different budget ranges.


Aircon-printed circuit boards play a crucial role in ensuring your comfort. These PCBs, acting as the brains of air conditioners, manage operations and conduct safety checks seamlessly.

Understanding and caring for them can significantly improve your AC’s longevity and performance. Repairing a faulty PCB is possible, offering a way to maintain optimal functionality without immediate replacement costs.

Knowledge about these components enhances your ability to diagnose issues early, making it easier to enjoy uninterrupted cool air.


1. What is a PCB in air conditioners?

A Printed Circuit Board (PCB) in air conditioners controls how the system operates by directing electricity through its circuits to power various components.

2. How are PCBs for aircon made?

PCB manufacturing for aircon involves designing the layout, fabricating the board with precise engineering techniques, and adding active components like dual-run capacitors to manage electricity flow.

3. Why do some PCBs have a liquid inside them?

Some PCBs use liquid in their design to help cool down the components or improve conductivity. This technique helps prevent overheating and ensures smooth operation.

4. What does it mean when a PCB is hermetically sealed?

When a PCB is hermetically sealed, it’s completely closed off from outside elements like moisture or dust with an airtight seal, protecting sensitive electronic parts within the circuit board.

5. Can flexible circuits be used in aircon PCB designs?

Yes! Flexible circuits can be incorporated into aircon PCB designs, allowing for more innovative layouts and better space utilisation within compact devices while ensuring reliable electrical connections between different system parts.

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