How does car air conditioning work?

An air conditioning system controls the temperature in a car and works in a similar way to a kitchen refrigerator. When the fluid inside such appliances (also called refrigerant) changes from a liquid state to a gas, it cools down. Outside air is blown past the coils in which the gas flows, and is therefore also cooled before it is blown into the car’s cabin. The air con gas then returns to liquid form in the system's compressor, heating it up, but the resulting warm air is directed outside the car.

Why is air conditioning important?

Air conditioning in a car serves two purposes. It cools down the interior of a car, dramatically so if needed, which improves passenger comfort and prevents the type of heat-related irritability that may lead to an accident. Also, because air conditioners generate air that is less humid than outside air, it can be used to demist a fogged-up windscreen more quickly than when air is blown out of a standard ventilation system. This might also prevent an accident from occurring.

What is an air conditioning system recharge/re-gas?

A simple check of the temperature of the air emanating from an air conditioning vent will tell you if the refrigerant needs a recharge - some garages use the term 're-gas'. A warm air temperature would suggest that the refrigerant is low or old. Manufacturers typically recommend a recharge no matter what every couple of years to keep the system running efficiently; this involves topping up or refilling the system with fresh refrigerant. This may be all that is needed, but an efficient air conditioning system also needs to be serviced occasionally. If the refrigerant is replaced but the air conditioning system does not seem to be operating properly, either due to warm air or low system pressure, an air conditioning service will be required.

What is an air conditioning system service?

If the pressure in the air conditioning system is particularly low, there might be a leak. This can be checked during an air conditioning service that manufacturers suggest performing every 3-4 years. As well as a test for leaks and the inspection of refrigerant levels, the condenser, the compressor, the hoses and the drive belts are checked. The service also involves a cleaning to take any contaminants, bacteria or moisture out of the system before any new refrigerant is added, followed by a full recharge. It is important to note that an air conditioning service is not included in routine car services but has to be booked separately. Remember to do so because an inefficient air conditioner places greater demands on a car’s engine and requires more fuel to generate cool air, not to mention that any resident bacteria might cause illness.

What causes air conditioning problems?

• Insufficient or old refrigerant.
• Low system pressure, typically caused by a leak or the failure of a component.
• Lack of use can place unexpected stress on components when the system is eventually turned on.
• The build-up of bacteria can make the air from your air conditioning system unhealthy.

What are the possible signs that a car needs an air conditioning service and recharge/re-gas?

• If warm air is blowing out of the vents.
• When the air conditioner only intermittently functions correctly.
• Foul smells emanating from the air conditioning vents are signs that mould and bacteria have infested the air conditioning system.

How long does an air conditioning recharge/re-gas and service take?

• A recharge takes about an hour; a service can take up to an hour.

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