Ah, how we love the quintessential British summer. Rained out bank holiday weekends, soggy barbecues hastily finished under a parasol – all made better by a solid run of sunshine and some blisteringly hot days.

Won’t stop us complaining, though! Even on a gorgeous, warm summer’s day, you’re guaranteed to hear an endless stream of “it’s too hot!” from at least a handful of people you know. That is, if it’s not you doing the complaining!

As a nation that seldom feels the heat, it’s uncommon to find air con in UK homes. But just about every car on the road has air con installed, providing its hot and bothered owners with a little respite from muggy heat at the height of summer.

So it’s always a bit of a nasty surprise when you get into your car on a hot day, blast the air con and get a faceful of smelly air that never cools down. That’s when you need a car air con service – but what happens in a car air con service to make your air con cold and fresh-smelling once again?

First, let’s take a brief look at how air con works in a car.


If you’ve ever had a car air con regas, you’ll know that your car’s air conditioning system periodically needs to be topped up with gas. But you might not know why.

The gas in question is a refrigerant, one of two refrigerants used in car air conditioning systems; R1234yf and R134a. This gas is an important part of a heat exchange process, one that might be familiar if you’ve ever used a can of deodorant – where the can gets cold as you spray it, or felt the cool perfume coming out of it.

Compressed gas gets cold as it changes state into a liquid, because it loses energy. As long as it stays compressed, it stays cold. When it’s released, it rapidly cools whatever it comes into contact with.

That’s essentially how your car air con works, too – except the gas is not released into the air. The refrigerant moves through a set of coils, released inside them as a gas, where it rapidly cools them down. The fans in your car’s climate control blow over the coils and you feel it as cold air. The refrigerant gas is then guided through the coils and compressed back into a liquid, where it loses energy and becomes cold again.

Over time, with this constant shifting of states, the gas can slowly leach away; even in a fully sealed system.

Of course, the compressor, coils and fans all play a vital role, too. If any of these systems should fail, then the heat exchange process won’t work. But a car air con service can identify common issues and fix them, or remedy them before they become bigger problems:

  • Low refrigerant
  • Damaged or leaking coils
  • Clogged or underperforming fans
  • Compressor failure
  • Compressor clutch issues

Some of these issues are more complex and costly to fix than others – and often, replacement parts are a better bet than repairing damaged ones. But what about that dank, musty air con smell?


Dirt and dust can collect in your car’s ventilation system leading to bacteria and mould formation in your air con system. That’s the cause of the musty smell wafting into your nose when you turn on the air con – and it can be especially noticeable if it hasn’t been used for a while. This is the most common reason for car air con smells.

This can be fixed with a deep clean of your car’s vents and air con system during a service, using antibacterial and mould-killing agents to keep the air con smelling fresh and clean for longer.

Sometimes, smells coming from your car air con can be from leaks; unwanted contaminants finding their way into the system.

Either way, strong smells coming through your vents should be inspected immediately, by booking your car in for a car air con service.


Smelly, never-quite-cool car air con? Let’s fix it for you; book your car air con service in Eastleigh with Master Tech Autos. Call us on 023 8061 1161 or book online today!

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