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Service Secrets ... Everything You Need to Know About Air Con

Service Secrets ... Everything You Need to Know About Air Con

It makes every car journey more comfortable on a hot sunny day ... until it stops working. Here's everything you need to know about your vehicle's air con and what to do if it smells a bit funky or starts blowing warm!

How does air con work?

The vital component in an air con system is the refrigerant, often referred to as the 'gas'. This substance goes on a journey through various components of your air con system to provide you with cool air ...

  • Before you turn on your air con system the gas is stored at low pressure. When you turn on your air con the compressor pumps the refrigerant at high pressure into the condenser.
  • Once in the condenser the high pressure causes the gas to condense into a liquid. This change of state produces heat which is removed by air from the outside flowing over the condenser.
  • The hot, high pressure liquid is then moved into the receiver dryer. Here any moisture is removed, and liquid is passed onto the expansion valve.
  • In the expansion valve the high pressure liquid is allowed to expand and become a gas once again.
  • In the evaporator the refrigerant is now a cold, low pressure gas. A fan pushes air from the outside of the vehicle over the outside of the evaporator where it is cooled by the refrigerant and then released into the cabin.

The whole process is continuous until you switch off the air con!

What is regassing air con?

The refrigerant inside the air con system shifts state from gas to liquid and gas again several times over and over again. Over these changes some of the refrigerant becomes lost so the level will slowly reduce. If left the level will eventually become so low that the air can no longer be cooled effectively, and air blows warm.

When you get your air con regassed, all the remaining refrigerant is removed from the system and any traces of moisture are removed to help prevent bacterial growth. Fresh refrigerant is then added to the required level.

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If your refrigerant levels are low, the air con system will need to work harder to produce cool air and so will use more fuel. Ensuring your air con system is working effectively will help with fuel efficiency.

Why is my air con not blowing cold?

The most common reason for air con not blowing cold is a low level of refrigerant. This can be easily remedied if you get your air con regassed.

However, if this does not work the next most common reason for air con to stop working is a leak in one of the pipes of the system. This allows refrigerant to escape.

Is air con maintenance included in a service?

The maintenance of air con is not commonly included in a service. Most car manufacturers will recommend you book an air con service roughly every 2 years. The exact recommendation for your vehicle will be found in your handbook.

Most air con services will replace the refrigerant and check for any leaks, cracks or damage in the system and will be completed within an hour.

Can a non-functional air con system cause an MOT failure?

While a non-functioning air con system may be annoying on hot summer days, it is not essential to the safe running of the vehicle, for this reason it is not checked during your MOT. Your MOT will not consider any features which are seen as luxuries or 'nice to haves' so you can still pass with broken air con.

Can air con irritate asthma or cause coughs and colds?

If you ever notice a bad smell coming from your vents it could be that bacteria have built up in the air con system. It is thought this could cause some people with respiratory problems issues, as the bacteria spores are then blown into the cabin and breathed in.

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Many garages will also offer an air con clean alongside the regassing service. This will involve using cleaning sprays which are circulated around the system that will kill any bacteria that have grown.

Air con and fuel efficiency

Using an air con system will use fuel so many people wonder whether it would be better to just open a window? Opening a window would not use fuel directly, however, open windows will make the vehicle less aerodynamic, so more fuel will be used to combat this. The faster you go the greater this effect. Many people choose to open their windows at low speed and use air con at higher speeds.

If you need your air con regassed and cleaned, you can click here to book at Rivervale or call the Service team on 01273 433480.

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The comments above do not necessarily reflect Rivervale's views unless clearly stated.

Driver advice
23 July 2018
Written by Natalie Faughy
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