What is an Air Conditioning System?
The whole system that cools, dries and freshens the cabin air.
Simplified animation — not to scale.
In plain English
Your air conditioning is a complete loop of components — compressor, condenser, expansion valve, evaporator and refrigerant — that work together to pull heat and moisture out of the cabin. It's the same idea as a fridge, just packaged into the car so you get cold air from the vents and a demisted windscreen on damp mornings.
"Like a fridge for your car — same parts, same physics, just spread out under the bonnet and behind the dash."
How it works
The compressor pressurises refrigerant gas, turning it hot. That heat is dumped to the outside air through the condenser at the front of the car. The cooled, still-pressurised refrigerant then passes through an expansion valve and suddenly drops in pressure inside the evaporator behind the dashboard — going bitterly cold. The blower fan pushes cabin air over the evaporator, which cools and dehumidifies it before it leaves the vents. Refrigerant typically needs a top-up (a "re-gas") every few years as it slowly leaks out through the seals.
Signs of trouble
- ⚠Air blowing from vents isn't as cold as it used to be
- ⚠AC takes much longer to cool the cabin
- ⚠Hissing or bubbling noises from the dashboard
- ⚠Damp or musty smell when AC is switched on
- ⚠Windscreen takes ages to demist
- ⚠Puddle of water inside the cabin (blocked drain)
£60 re-gas to £1,500+ for major fixes
Always get a written quote. Prices vary by car, region, and parts brand.