Summer is here and boy it’s here to stay. Be your daily office commute or a weekend getaway, travelling without AC is going to be dreadful and hellish. Given that the temperature inside the car cabin can rise up to 60°C, checking up on your car AC should be your top priority. There can be a host of issues creeping like low cooling, bad odour, failed compressor and what not. Although regular AC maintenance should be a ritual, It is generally prescribed to get a full car AC service every year to keep the cooling at maximum efficiency. So, why wait? Bring down your car to a nearest GoMechanic workshop for a full car AC service at the best price in your city.

How a Car AC work? Automotive Air Conditioning Explained
Car AC Service Explained

In this blog post, we are going to elaborate on what goes inside with an AC service. Learn more on vital AC components, common AC issues and how you can easily maintain your car AC at home! Read more.

How A Car AC Works

let’s get some insight on what makes a car AC functions ie. the components. Starting with the;

  • Compressor
    As the name suggests, is responsible for compressing the refrigerant. It works like a pump that pressurises the refrigerant and passes it on to the evaporator. The compressor is driven by a drive-belt which also powers the power steering, water pump etc.
  • Refrigerant
    It is a fluid that is contained within the coils of a car AC system that makes the whole cooling thing possible. The most common refrigerant used in Car AC is the R134-a, also known as Tetrafluoroethane. Prior to 1993, the most widely used refrigerant was the R-12 a.k.a Freon which was quickly replaced due to its harmful environmental impact.
  • Condenser
    A condenser is a mesh of coils arranged in a zig-zag pattern that removes the heat from the compressed gas. It acts as a heat exchanger which cools the refrigerant changing its state from gas to liquid.
  • Evaporator
    The evaporator is quite opposite to a condenser. It converts the liquid refrigerant back to its gaseous state simultaneously dissipating the heat and cooling it further. It is located inside the car typically hidden behind the dashboard.
  • Expansion Valve
    The expansion valve works in tandem with the evaporator to control the pressure of the AC refrigerant through the AC system.
  • Dryer/Accumulator
    The dryer unit contains desiccant which is responsible for pulling away moisture that can seep into the AC system and the cabin.

Turn on the blower, push the AC button and enjoy the cool and comfortable cabin.

Well, there is more to it. When you switch on the AC, the compressor kicks in using some power from the engine. It then compresses the refrigerant present in the AC system causing it to liquefy. The liquified refrigerant then travels to the condenser, which pulls the heat out using fresh air assisted by a fan. The refrigerant then flows through the expansion valve where the pressure is checked and regulated. Further down the line, the dryer pulls out moisture or impurities from the system. The now cool and clean gas is passed through the evaporator fins where a blower fan pushes the cold air out of the dashboard vents. The refrigerant is then pulled back to the compressor where the cycle starts all over again.

Car AC Service: A to Z

How a Car AC work? Automotive Air Conditioning Explained
Car AC Service Explained

When you take your car for a car AC service, the technician starts by checking the cabin temperature while operating the AC (should be approx 5-10°C). He then proceeds to check the level of the refrigerant present in the system. A low refrigerant level is the most common cause reported for a low cooling car AC. Using a pressure gauge and a precision AC gas recharging machine, the refrigerant level is flushed and topped-up to the recommended level.

While working on this, a possible leak or crack in the AC line and hoses is also checked for. The technician may use a UV dye to better pinpoint a possible leak in the system.

Then comes the compressor, which is the most expensive component in a car AC system. The compressor is what powers the whole system if the compressor fails, the whole AC system will fail.  If there is a visible leaking or the compressor is making a whirring noise while operating, a bad seal or a bearing can be an issue. The best way to keep a compressor working is to get it checked and serviced every year, making sure to replace the compressor oil.

The condenser, which resides in front of the engine is checked for bent/damaged fins or a clogged line. A clogged condenser due to leaves, dust and debris build-up can really bring down the cooling efficiency of the AC. In such a case, the condenser is washed using mild water pressure so as to not bend the fins.

Furthermore, the dryer is checked for proper function with a final inspection of the evaporator for any moisture build-up which can seep into vital electrical components under the dashboard

Finally, the cabin filter or the HVAC filter (heating, ventilation, air conditioning) located under the glove box is cleaned or replaced (replaced every 15,000km).

5 Common Car AC Problems (with Troubleshooting)

  • Car AC not cooling enough
    This can be due to low refrigerant level or a failed compressor, which can be quite expensive to fix or something as easy as a clogged condenser, which decreases the surface area of the coil resulting in less cooling.
  • Bad odour from AC
    A very commonly reported car AC problem. A faint or strong foul smell means, mould/mildew or moisture formation in the AC filter. Cleaning or replacing the filter usually solves the problem. But if you smell “rotten eggs” while operating the AC, there can be pest invasion or a dead animal somewhere in the system which should be strictly handled by a professional.
  • Loud whirring noise
    Loud high-pitched whirring noise while operating the AC can be due to a shot compressor bearing (in case the noise is coming from the engine bay). If the noise is coming from inside the cabin, the blower fan assembly needs a repair or a replacement.
  • Water Seeping inside the cabin
    When the refrigerant flows through the evaporator, it gets condensed, forming water. If the drain tube which directs the water outside is blocked, you may notice water inside the car cabin.
  • Engine overheating
    Just like the steering or the water pump, the compressor uses some power from the engine (using the serpentine belt). The clutch on the compressor can cease causing the compressor to put an unnecessary load on the engine causing overheating.

Car AC Maintenance: DIY

Need for Car AC inspection
Car AC Service Explained

Car AC service is a must and a responsible car owner should get the car AC serviced every year for maximum cooling efficiency. Here a few steps you can take to better maintain your car AC, that too at home!

  • Wipe the vents
    Did you know? all that dust on the AC vent can eventually accumulate and clog-up the cooling coil causing a drop in cooling. Using a brush or a sponge and gently clean the AC vent every once in a while.
  • Clean the cabin filter
    The cabin filter or the HVAC filter located behind the glove box can get dirty and clogged due to dust and debris filtering from the outside. Mould and mildew can also form which can lead to foul odour while operating the AC. You can easily service the AC filter using a brush to clean the fins. Spray a deodoriser before installation for better results.
  • Clean the condenser
    The condenser is located behind the front bumper of the car. It is made of aluminium fins and line which take in fresh air assisted by a fan to cool the flowing refrigerant. Make a habit of hosing down the condenser with low-pressure water to dislodge stuck leaves, debris or dust which can bring down the cooling.


  1. I am really very much worried about bad smell from my ac vent, I found the reason of that from your blog.

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