Car Air Con: How to Use It and Keep It Working

Most people think of air con as a summer thing. It isn’t. Used properly it clears a misted screen faster in winter, and running it regularly is the easiest way to keep it working.

Run it all year

The gas in the system carries oil around with it, which keeps the seals and the compressor lubricated. Leave the air con off for months and the seals can dry out, which is how small leaks start.

Running it for ten minutes or so every couple of weeks, even in winter, keeps it healthy.

Use it to demist

Air con dries the air as well as cooling it. On a cold, damp morning, put the heat up, the fan on the screen and the air con on, and it’ll clear much faster than heat alone. A lot of cars switch the air con on automatically when you press the demist button for exactly this reason.

Turn recirculation off while you’re demisting. Recirculated air is the damp air that’s already in the car.

Signs it needs looking at

• It doesn’t blow as cold as it used to
• A musty or damp smell when you switch it on
• It takes ages to clear the screen
• A rattle or squeal when the air con kicks in
• Water in the passenger footwell

What a regas is

Over time the system slowly loses gas, even without a leak. A regas takes the old gas out, checks the system holds pressure and refills it with the right amount. If it’s lost a lot, there’s probably a leak, and it’s worth finding before refilling.

There are two types of gas. Most cars up to around 2016 use R134a, and most newer cars use R1234yf, which costs a lot more. That’s why newer cars cost more to regas, wherever you go.

Smells and bacteria

A musty smell usually comes from bacteria and mould on the evaporator, the part behind the dashboard that gets cold and wet. An antibacterial clean kills it off, and a new pollen filter helps keep it away.

How we do it at GT

An air con regas is £72 for cars using R134a (most cars up to around 2016) and £108 for R1234yf (most newer cars), with an antibacterial clean included. We check the system holds pressure before we refill it, so you’re not paying to fill a system that’s leaking.

See our air con service →