When it’s hot outside, you’ll certainly want to seek cool relief when in your car.
The air-conditioning systems of modern vehicles have been designed to set air-conditioning at the press of a button (auto), but do you know what happens in the background?
Air-conditioning systems operate in a similar way to a household fridge in that they use pressure to transform liquid into an icy cold gas, that the fan blows through in order to make the cabin cool.
How to make air-con more efficient?
On a hot day, the inside of a vehicle can reach temperatures over 60C, which is why you should never leave children or pets unattended.
To help reduce the cabin temperature, try to park in a shaded area and use a windscreen shade to keep the heat off the dashboard.
This will not only keep the dashboard and vents cool, but also stop the steering wheel from getting hot and uncomfortable to hold.
If your vehicle has been sitting in the sun all day and is like a sauna, it’s best to open all the windows for a few minutes to expel the heat before turning on the air-conditioning.
Driving with the windows down will also force hot air out much quicker.
For the best cooling results, once you have removed the hot air from the cabin, close all the windows and then use the air conditioning in recirculation mode.
This will help circulate the already-cooled air, which is more efficient than continuously drawing in warm air from outside.
However, don’t use the recirculation mode for too long, as the air in the cabin could get a bit stuffy and make the driver drowsy.
A blast of fresh air from an open window will help, or switch off the recirculation button and put the A/C back into auto mode.
Does air-con use more fuel with windows down?
Driving with the windows down can create wind disturbance, which lessens the vehicle’s aerodynamics, and means more effort is required to push the vehicle along.
Air-conditioning can put extra load on the engine while in operation, causing the engine to use more energy and fuel. We would recommend a balanced compromise — perhaps wind the windows down at low speeds, and set the air con for use on the highway to reduce drag, cabin noise and disturbance.
It’s important to remember that a vehicle’s A/C system is run by a belt attached to the engine, so it operates only when the engine is running.
Don’t be fooled by the few seconds of cold air circulating once the engine is switched off. Vehicles can quickly become oven-like once cool air stops.
Why is water under the car after using air con?
The chilled gas passing through the evaporator creates condensation which freezes and melts. It is then drained outside via a hose beneath your vehicle.
If the hose is blocked or disconnected, water can leak on to the floor by your feet.
If you don’t see a puddle under the car after you have used the air con, make sure everything is working as it should be.
Keeping your air-con operating effectively
Regular cleaning or replacement of the cabin filter (if equipped) will ensure air drawn into the cabin is free from leaves, pollen and pollutants that can gradually clog the filter.
Over time, you may notice the system isn’t as cold or effective as it once was. The refrigerant may gradually lose its pressure and might require a top-up, or there may be a fault that has caused gas to leak. If this happens, talk to your local mechanic.