Complete Guide to PCB in Aircon: Core Techniques Explained

Another small detail that many people easily overlook is the mechanical stress during installation. Over-tightening screws or uneven circuit board assembly can cause premature aging of the pins. I myself encountered a case where an overly tight mounting clip caused a slight deformation of the PCB. Although it tested fine initially, after six months of use, a pin detached from its pad.

Good air conditioner brands now reinforce the back of the PCB, especially around the IPM area. This is effective, improving heat dissipation and reducing vibration. However, ultimately, the most fundamental thing is to understand the operating environment of each component; you can’t just look at the impressive specifications.

Having worked in air conditioning repair for a while, you’ll notice an interesting phenomenon—many people assume poor cooling is due to low refrigerant or a broken compressor. Often, the problem lies with that small circuit board. I encountered a case last week where a customer reported that even with the air conditioner set to 26 degrees Celsius, the room was still stuffy. Upon inspection, the outdoor unit’s fan was found to be spinning extremely slowly. Upon disassembly, the capacitors on the PCB board were bulging.

This situation is particularly common in older residential areas, especially in units installed in western-facing locations. Prolonged exposure to direct sunlight causes internal temperatures to easily exceed 85 degrees Celsius. Electronic components operating in such an environment are like people working overtime in a sauna every day—it’s bound to cause problems sooner or later.

I remember once discovering an even more subtle issue while performing maintenance on a hotel. A dozen or so air conditioners from the same batch were all displaying error codes. It turned out that the PCB board of these machines had a design flaw: the solder joints of a certain component were too close together. Under large temperature differences, this could easily cause micro-short circuits. Such problems are difficult to detect without rigorous environmental testing.

Many manufacturers now simplify their verification processes to save costs, such as omitting temperature cycling tests. This actually creates hidden dangers. I usually advise customers to avoid installing outdoor units in direct sunlight. If that’s unavoidable, add a sunshade.

A recent unit I repaired left a deep impression on me. The user reported a burning smell during operation. Upon inspection, it was discovered that the power module’s heatsink was installed backwards. This assembly error should have been detected during pre-shipment functional testing.

Some repair technicians like to replace the entire control board directly. I think a detailed inspection should be done first. Measuring the voltage values ​​at each node with a multimeter can pinpoint most problems.

Actually, PCB boards have a longer lifespan than many people imagine. As long as regular cleaning is done to prevent dust accumulation and attention is paid to heat dissipation, it’s normal for them to last eight to ten years.

What frustrates me most is that some users install the outdoor unit in an enclosed balcony.

Poor heat dissipation causes the mainboard to operate at high temperatures for extended periods. Even the best quality boards can’t withstand this. Every time I encounter this installation problem, I have to spend half a day explaining the importance of ventilation to the user.

Ultimately, air conditioning is a system engineering project. The circuit board is just one part. But if this part has a problem, the entire system will be affected.

Therefore, when buying air conditioners now, I pay more attention to the manufacturer’s quality control processes. Companies that dare to publicly disclose their test data are usually more reliable.

After all, publishing the test results of the PCB board running continuously for 1,000 hours at 85 degrees Celsius demonstrates confidence in their products. This is far more reliable than listening to salespeople boast about cooling capacity.

I recently encountered a particularly interesting situation: my old air conditioner suddenly stopped working. Opening the control box revealed the problem immediately—something was wrong with that small green board. Many people might think that an air conditioner not cooling means it’s low on refrigerant or the compressor is broken, but often the problem lies with the tiny circuits on the PCB board, especially in older machines that are seven or eight years old.

Think about it, the internal environment of an air conditioner is actually quite harsh. In summer, it operates at high temperatures and humidity, and in winter, it has to cope with low-temperature startup. Under these conditions, the copper foil traces on the board are particularly prone to aging. The most extreme example I’ve seen is a neighbor’s air conditioner board with verdigris, and the circuits were broken. In such cases, repairmen often directly recommend replacing the entire control board.

The issue of chips is even more interesting. Many air conditioners now cram too many functions into a single main control chip in pursuit of functional integration. The result is poor heat dissipation, making it prone to burning out with even slight voltage fluctuations. The air conditioner I helped a friend repair last week was like that. What seemed like a minor issue—the outdoor unit fan not spinning—turned out to be a partial failure of the main control chip.

Actually, I think there’s a design flaw in modern home appliances: the wiring is often made too dense. Especially with power and signal traces, if they’re too close together, they easily interfere with each other. I once saw a returned circuit board that had this problem; the control signal was malfunctioning, the compressor kept starting and stopping, and it eventually became completely unusable.

What’s most frustrating is that some faults are very subtle. The board may look perfectly fine on the surface, but it just doesn’t work properly. In these cases, it often takes a lot of time to find the real failure point. That’s why I now habitually start by checking the simplest part of the power supply when repairing air conditioners; it saves a lot of time.

Many people think that if an air conditioner isn’t cooling well, it’s just low on refrigerant, but often the problem lies with that small PCB inside.

I’ve seen too many air conditioners fail prematurely due to PCB failure. Especially if the design isn’t well thought out, repairs become incredibly difficult.

Dust has a more serious impact on PCBs than most people realize. My old air conditioner had a problem last year, and when I opened it, I found a thick layer of dust on the circuit board. This dust not only affects heat dissipation but also absorbs moisture from the air, causing short circuits.

Many manufacturers, in order to save costs, don’t do a good job of protecting their PCBs. A friend of mine had an air conditioner that started frequently shutting down after only two years of use. After inspection, it was found that dust covering the components on the circuit board triggered the overheat protection mechanism.

In fact, the reliability of a PCB largely depends on the initial design. Some engineers like to cram components in densely packed areas, which saves space but creates conditions for dust accumulation.

I think the ideal approach is to reserve sufficient heat dissipation space during the design phase and consider dust prevention measures. For example, you can install finer filters at the air inlets or optimize the airflow design to prevent dust from accumulating in critical areas.

I remember once helping my neighbor repair their air conditioner and finding that their PCB layout was very reasonable. Important components were placed in well-ventilated locations, and the board surface had a special treatment that prevented dust from easily adhering.

Of course, even the best design cannot withstand long-term neglect. I recommend cleaning the indoor unit’s filter at least once a year to significantly reduce the amount of dust entering the unit. If you live in an area with poor air quality, you’ll need to clean it even more frequently.

Ultimately, the lifespan of the PBC (Printed Circuit Board) depends not only on its own quality but also on the usage environment and maintenance habits. Paying more attention to routine maintenance can often prevent many unnecessary repair problems.

Sometimes I think it would be great if manufacturers could more clearly remind users of the importance of dust prevention in the instruction manual. After all, most people don’t realize that seemingly insignificant dust can cause such significant damage to the core components of an air conditioner.

While newer air conditioners have indeed improved in this regard, I still think protective measures could be more thorough. Replacing a PCB is quite expensive; it’s better to take preventative measures from the start than to wait until problems arise.

In short, the PBC is like the heart of an air conditioner; it needs to be properly protected.

Many people fall into a misconception about air conditioner circuit boards, thinking that as long as the components are good enough, everything will be fine. However, the choice of board material is the real key to determining the product’s lifespan. I’ve seen too many cases where entire batches of products had to be returned due to board material issues.

I remember once testing circuit boards made of different materials under the same working conditions. A board made of ordinary materials deformed after three months, while a board made of the appropriate materials lasted for two years without any problems. This made me realize that in equipment like air conditioners that operate for extended periods, the thermal stability of the board material is paramount.

Currently, many manufacturers, in an effort to save costs, often overlook a crucial indicator when selecting components: the material’s ability to withstand high temperatures. Imagine an air conditioner’s outdoor unit in summer; under direct sunlight, the internal temperature can reach 70-80 degrees Celsius. Add to that the heat generated by the components themselves, and ordinary materials simply cannot withstand this continuous thermal shock.

I pay particular attention to the performance of the board material during processing, such as the punching process. If the material’s toughness is insufficient, micro-cracks can easily form at the edges during punching. These invisible damages accumulate over time. Thermal expansion and contraction can gradually cause circuit breakage, which is why some circuit boards that pass lab tests fail after only one or two years of actual use.

Another easily overlooked point is that different power levels of air conditioners have different requirements for the board material. High-power models generate more heat and require specially treated materials, while ordinary wall-mounted units can have more relaxed standards. However, this doesn’t mean you can choose any material; each product should have a corresponding selection plan.