Common Car Air Conditioning Problems

Our air conditioning systems play a pivotal role when it comes to being comfortable on both long and short car journeys. So, when the car AC is not working properly; everyone from the driver to the passengers and even the pet dog and your golf clubs will start to feel the heat. From helping you to stay fresh and cool on the roads in the warm summer sun, through to demisting your windscreen in wintry weather; when it comes to comfort and convenience we rely on our car’s air conditioning system more than many of us realise. 

There are a few common problems that can impact how effective your auto air conditioning is but the good news is that many of these issues have simple solutions. 

Regular maintenance can help your auto air conditioning to stay fresh and cold throughout the year and many problems can be easily resolved, whether your air con is blowing out hot air or it simply won’t turn on. At ATS Euromaster, we offer a range of useful services, from recharging to anti-bacterial cleaning, and these will help to ensure that your car’s air conditioning is working at an optimum level - whatever the weather is doing. 

Most Common Problems With Car Air Conditioning

Simply click the links below to jump to your specific problem and our recommendations


My Air Con Smells Bad

Are you greeted with a less-than-fresh smell when you switch on your air con? A good sign that your car AC is not working is when they give off a rather unpleasant whiff, caused by a variety of problems. 

Damp Smell

The distinctive smell of mildew flooding out of your air vents is usually caused by a build-up of bacteria and mould. This can happen to older cars that have had bacteria growing behind the dashboard for years and in cars that rarely run the air conditioning, as they are don’t enjoy the drying effects that it provides to excess water on the coils. 

Pungent Odours 

A generally bad smell can be emitted when the air filters get clogged up with dirt, dust and stagnant water and this odour can be repulsive enough to make drivers switch off their auto air conditioning, rather than suffer through the smell.

Chemical / Sweet Smell 

When a chemically, sweet smell is given off when you turn on your air conditioning, it is likely that there is a leak somewhere within the system, most likely in the hose, pipe or heater core, the radiator or the housing unit for the coolant. 

A Smell of Gas 

A gas leak can be detected in your auto air conditioning unit when a smell of gas is emitted when you turn on the system. The waft of gas often appears when the system is first turned on and the fresh air is sucked into the vents, pushing out the gas that has built up inside the unit. 

All of these smells can indicate that your car AC is not working and that there is a problem within your air conditioning unit, from dirty air filters that need to be changed to leaks that need to be repaired and vents that need to be cleaned. Find out more about what to do if your air conditioning smells. 

Recommended Service

Want to freshen up your car air con? Book an anti-bacterial clean online to rid your car air conditioning system of any undesirable or musty smells.


My Air Con is Blowing Hot Air/not Cold

We spend the winter months looking forward to the promise of the warm spring sunshine and while the change in weather is always welcome; for those with faulty air conditioning; driving can quickly become hot and frustrating. 

Being too hot in a car is unpleasant for everyone, from drivers to passengers, and one of the worst experiences is when you jump into your muggy car, only to be greeted with nothing but hot air blowing out of the air conditioning unit. 

So, just why is your car air con system blowing hot air? 

The main culprits when it comes to identifying this particular problem are:

  • Damaged cooling fans
  • A blocked or broken condenser
  • An internal obstruction
  • An electrical fault 
  • Low refrigerant levels


Often, when an air conditioning unit is blowing out hot air the underlying problem as to why your car AC is not working can be identified during a simple visual check conducted by an ATS Euromaster technician. 

Do you suspect that your car’s air conditioning unit might have a problem? Stay cool on the roads in the summer and demist your windscreen in the winter with our air conditioning services available at your local ATS Euromaster centre.  

Recommended Service

Air Con Regas

My Air Con Won’t Turn Off

Another common problem with car air conditioning systems is when the system won’t turn off and in extreme cases; the unit will continue to run even when the engine is switched off which will eventually drain the battery.

This problem can occur for several reasons, including:

  • Faulty or loose ribbon cable Broken controls/dial stuck in the “on” position
  • Broken selector switch Shorted blower resistor
  • Shorted blower motor relay Shorted A/C controller
  • Shorted blower control circuit

Not being able to turn the auto air conditioning system off is a problem that needs to be rectified for a number of reasons, such as reducing the amount of fuel that is used to power the system and not getting overly cold when behind the wheel.

Recommended Service

Contact your local centre to get this looked into before you book anything.

My Air Con Won’t Turn On

While not being able to turn the air conditioning off is a problem, not being able to turn it on in the first place is arguably worse - whether you rely on it to help you to demist your windscreen in the winter or to keep you cool behind the wheel in the summer. When the AC in a car is not working, driving can be an unpleasant experience.

So, what should you do if your air con won’t turn on? Get help from a trusted ATSE technician, as even something as seemingly small as a slight increase in temperature while it’s running can indicate a much bigger problem. On extremely hot days, an air conditioning system can overheat and this can cause the fan to burn out.

A broken dial can also affect your ability to switch the auto air conditioning on, as well as a broken switch, a stuck valve, a wiring fault, a blown fuse or an obstruction in the air ducts. Many car owners make the mistake of not running their air conditioning during the cold winter months.

Car AC compressor won’t turn on: The majority of compressors won’t engage if the coolant level falls too low, so an easy way to diagnose if this is the problem is to see if you can hear the compressor kicking on and off.

If the battery has been disconnected, it may be necessary to take the car to the manufacturer to get the computer reset as the electronics are prone to going into an unintelligible condition after the battery has been detached.