Air Conditioning of Gasoline and Electric Vehicles

A vehicle's A/C system is a completely sealed circulation system, mainly composed of three key components: the compressor, condenser, and evaporator. Additionally, there are parts like the expansion valve, dryer, and fan. The compressor is connected to the engine by a belt, so it only operates when the engine is running, enabling the entire A/C system to function.

Steps of Operation of Vehicle Air Conditioning

1. The compressor sends high-temperature, high-pressure gaseous refrigerant to the condenser at the front of the car, where the refrigerant turns into a liquid due to the temperature difference.
2. The liquid refrigerant passes through the dryer and expansion valve before entering the evaporator.
3. The liquid refrigerant absorbs the heat from the air pulled in by the fan and turns into gas.
4. The fan blows cool air into the cabin through the vents.
5. The gaseous refrigerant is sucked back into the compressor for a new cooling cycle.

Since the compressor depends on the engine's rotation to operate, the higher the engine speed, the better the cooling effect. To ensure adequate cooling even when the engine is idling, a compressor with a larger capacity is needed. The downside is that this also increases fuel consumption.

Early electric vehicles (EVs) used A/C systems similar to those in gasoline vehicles, but the compressor was powered by a motor instead of an engine. Newer EVs use an integrated compressor which houses the compressor, motor, and circuits in one unit, with the benefit that the burden on the vehicle's drive system is not increased. The compressor motor can adjust its speed, meaning the compressor can have a smaller capacity than those in gasoline vehicles, leaving more electrical power for the drivetrain.

The A/C system involves many components, and a problem with any part can affect cooling efficiency.

Refrigerant

When the A/C isn't cool enough, the first thing that comes to people’s mind is often the refrigerant, leading them to refill it at a garage. Although adding refrigerant usually restores the temperature instantly, it typically only lasts for a short time. Since the A/C system is a completely sealed system, insufficient refrigerant means there is a leak somewhere, which should be thoroughly checked for at a garage.

Compressor

The compressor is the heart of the A/C system, and any problem with it directly affects the system’s operation. However, since compressors are generally durable and there can be many possible causes for the same issues, compressors are usually checked after everything else has been. Unfortunately, by this point, a lot of money and time are already spent. Moreover, replacing the compressor is costly, making compressor issues a significant headache for vehicle owners.

Damaged/Blocked Condenser

Located at the front of the vehicle, the condenser uses the airflow for the cooling process while the vehicle is driven and is therefore subject to dust and debris impacts. Over time, the accumulation of dust reduces its efficiency. What’s worse, frequent expansion and contraction due to temperature changes can cause cracks, resulting in refrigerant leaks.

Cooling Fan

The cooling fan is installed behind the condenser. Common problems include motor or circuit issues, causing the fan to stop working and affecting the cooling effect.

Expansion Valve

The expansion valve is for regulating the temperature by adjusting the amount of refrigerant entering the evaporator. If the expansion valve fails, it can cause a loss of system pressure, disabling temperature regulation.

Air Conditioning Filter

The A/C filter is usually located inside the glove box and is used to prevent matters including dust and leaves from entering the cabin through the air ducts. If not replaced for a long time, it can reduce airflow and affect air quality. It is recommended that this filter be replaced at least every six months.

The small cabin space makes even a slight odor noticeable, affecting driving comfort. Odors can come from the A/C system, or they can come from other sources.

Moldy Evaporator

When the A/C is running, moisture from the air accumulates on the evaporator. If the driver turns off the engine immediately after parking, the water droplets will remain on the evaporator. Combined with dust accumulation, this can easily lead to mold growth over time, resulting in a musty smell from the A/C.

Air Ducts

Cool air reaches the cabin via the air ducts. Due to temperature differences, moisture can accumulate inside the ducts, promoting bacterial growth and producing odors. If the situation is mild, vehicle air conditioning cleaners can be used, but it's important to read the instructions carefully and pay attention to where the cleaner is to be sprayed.

Air Conditioning Filter

A dirty A/C filter not only affects cooling efficiency but also produces odors. Prolonged use without replacement can even impact health, so it’s worth reiterating that the filter should be replaced at least every six months.

Excessive Fragrance

Many car owners like to place fragrances in their car, but if the fragrance contains volatile ingredients, the scent can cling to the evaporator and air ducts over time. Combined with humid weather, this can create unpleasant smells.

Environmental Odors

Sometimes, while driving, you may suddenly notice an odor, but can't find the source inside the vehicle. In fact, the smell might not come from within the car but from the outside, which gets drawn into the cabin through the external air circulation. In this case, switching to internal circulation should resolve the issue.

Car A/C problems can be costly and time-consuming to repair, causing significant frustration for car owners. However, regular and suitable maintenance can reduce the likelihood of these issues.

1. Turn off the A/C system a few minutes before reaching your destination but keep the fan running to dry the evaporator and air ducts’ interior. This can reduce moisture buildup.
2. Avoid running the A/C in the lowest fan speed for extended periods, as this can lead to dust accumulation inside the air ducts. Periodically run the fan at the highest speed for a few minutes to clear dust from inside the ducts, but ensure everyone exits the cabin first.
3. Cold air sinks, so it's best to slightly tilt the vents upward when using A/C to feel cooler and reduce the system's workload.
4. When entering a car in hot weather, many people turn on the internal circulation to cool down faster. However, since the temperature inside the car is higher than outside, this can have the opposite effect. Instead, open the windows, set the A/C to external circulation to expel hot air quickly, and switch to internal circulation only after the cabin air temperature has dropped.