Everything You Need To Know About Your Car AC: 3 Key Facts [As Of 2023 ]

You may take it for granted, but your car’s air conditioning system is part of what makes long road trips under the gruelling heat enjoyable.


There’s nothing like the cool air hitting your face as you’re stuck in perilous traffic or taking an almost 8-hour drive to Malaysia with your family. Your air conditioning system is necessary, yet surprisingly taken for granted.


So, when the time finally comes that the aircon system stops working, you wish you’d taken all steps to ensure your car air conditioning still works. Now you mourn the loss of cool air as you navigate Singapore’s urban jungle in sweaty, scorching hot temperatures.


But diagnosing problems with your car air conditioner is no walk in the park. It requires basic knowledge of how car air conditioning systems work and how it uses up the surrounding hot air to produce cold air.


Though we’re not going to go into specific details that you’d be better off leaving to your trusted mechanic, understanding air conditioning mechanics is vital in identifying and solving potential issues early on.


Below is a brief guide on air conditioning systems every car owner must know.

Admit it: The only thing you know about your aircon is that it produces cold air. But a more complex interplay between physics and thermodynamics is involved.


When you turn on the air conditioner, the compressor compresses the refrigerant or coolant. This causes the temperature to rise, gradually losing heat as the refrigerant passes through the condenser.


The refrigerant starts passing through the receiver/dryer, effectively removing contaminants and moisture. Then, it loses pressure and temperature at the expansion valve before it flows to the evaporator.


The evaporator coil is a part of the air conditioning system which releases cool air in the cabin. It’s the medium by which the refrigerant (also known as coolant or freon) changes states from liquid to mist or cold vapour.


The vapour is pushed outwards through the ventilation system blower motor, bringing fresh and cold air into the cabin or passenger compartment.

Parts Of An Automotive Air Conditioning System

Though air conditioners seem to work as a single vehicle component, car air conditioners have several essential parts, such as:




This is the air conditioning system’s power unit which increases the pressure of the refrigerant before pumping it into the condenser.

A fully-functional compressor is vital so the air-con system performs optimally.




Condensers are usually located in the front of the vehicle, specifically in front of the radiator. It’s sometimes referred to as a mini-radiator, as it is primarily involved in heat exchange.


Air conditioning condensers lower the refrigerant’s temperature and then change it into a liquid state by transferring the heat to the ambient air passing through the condenser.




The dryer has three main functions. One is to trap debris and other contaminants in the air conditioning system.


Secondly, when oil and refrigerant are not necessary for operation (like in periods of low cooling demand), the dryer serves as a temporary storage container for the refrigerant.


Finally, the dryer also contains a desiccant which absorbs moisture that can get trapped in the component during manufacturing.




The evaporator absorbs heat, transforming the refrigerant into vapour. This process generates cooling air, which is blown across the evaporator.

Some tell-tale signs of a damaged evaporator include:


  • Hair air blowing through the cabin
  • Musty odour
  • Weak wind gusts coming out of the grille


Metering Device


Every car air conditioner system has a metering device. This component regulates or controls the amount of refrigerant that passes through the entire system.


Metering devices usually are in the form of an expansion valve or orifice tube mounted on the air conditioning unit’s high-pressure side, sandwiched by the dryer and firewall.

Common Car Air Conditioner Problems

Many car owners will agree that there’s an issue with an air conditioning unit expelling warm air. Sometimes, the problem may be that the unit takes an incredibly long time before it releases cold air.


These are good signs that it’s time to bring your car to a precise auto service provider that can diagnose common car air conditioner problems, make repairs, or replace parts.


Nevertheless, it’s essential to be aware of other common car air conditioning problems to prevent damaging your unit.


Unable To Turn Off The Air Conditioning System


This issue may seem strange, but it’s a fairly common car air-con problem. Even after turning off your engine or all accessories, the air conditioner continues to run.


In such cases, look for issues in the following components:


  • Dial
  • Selector switch
  • Ribbon cable
  • Blower resistor
  • Control circuit
  • AC controller
  • Motor relay


Fixing these issues can take considerable fuel usage, so it’s best to have your air con checked by a professional car mechanic.


Unusual Smell Coming From The Air Conditioning Unit


Auto air conditioning systems are designed to filter polluted air to ensure only fresh air enters the cabin. A sign there’s a problem with the unit is if it starts producing any of these unusual odours:


  • Sweet/Chemical Smell – Detecting a sweet odour from your air conditioner might mean a leak inside the system. We advise you not to fix this issue yourself, as it could lead to more harm than good. Have it checked by an automotive technician instead.
  • Damp/Musty Smell – Damp odours are frequent in old vehicles, especially those which have not been used for long periods. Also, older cars that are often left in hot and humid conditions can lead to bacterial buildup, causing a damp smell. Avoid this issue by having your car regularly washed. It’s also a good habit to turn on its engine and drive it for at least 20 minutes once a week (when irregularly used).
  • Gas-Like Smell – When the air coming from the unit smells like gas or fuel every time you turn it on, there’s likely a gas leak. These fumes are syphoned from the unit and released directly into the vehicle cabin. Don’t try to delay a visit to your local auto repair shop if this happens since inhaling these fumes can be toxic to the body.


Car Air Conditioner Is Not Turning On


Several reasons could point to why your A/C refuses to turn on. It could be due to a clogged filter, a problem with the radiator, or the system may be due for a recharge.


Other possible causes include the following:


  • Overheated car air conditioner
  • Non-functional dial or switch
  • Constantly putting the air conditioner in “sleep mode.”
  • Low refrigerant or coolant levels

While the car air conditioner is one of the most critical components of any vehicle, car owners tend to overlook this part.


Air conditioners cool the car’s interior and provide fresh air to drivers, especially during long rides. Riding or driving a car can be uncomfortable once the unit stops working due to poor air flow or circulation.


Now that you’ve read vital information about car A/C systems and how they work, you’ll have a better grasp of what to look out for once it starts functioning poorly.


Need to have your car air conditioner checked? Visit Kee Yong Auto here at our car workshop in Sin Ming.


We offer a range of car servicing packages in Singapore for different makes and models, such as Mercedes-Benz, Bentley, Jaguar, Land Rover, Porsche, BMW, and many more.


Contact us for more information so we can learn how to serve you better.

How Often Should I Recharge My Car Air Conditioner?

It’s advised to have your car’s air conditioner recharged once a year or every two years. It’s advisable to schedule an AC recharge even before the unit stops functioning properly.

How Do I Take Care Of My Car Air Conditioner?

Here are some basic car AC maintenance tips all car owners can use:


  • Defrost the air con for at least five minutes
  • Dust your air conditioner to remove contaminants
  • Don’t set the thermostat too high
  • Turn on the air conditioner during humid weather to avoid fogging in windows
Do Car Air Conditioners Use Up Fuel?

Yes. Car air conditioners can use up to 20% of fuel due to the load on the engine. This figure can vary depending on the vehicle’s interior size, outdoor temperature, and other factors.

Is It Okay To Run Car AC While Parked?

Yes. Turning on the AC while parked generally won’t cause harm to your engine, so long as the cooling fans work. Modern cars are designed to run all day, even with the AC on.