Why isn't my air con cold?

Every summer when the weather gets warmer we have lots of customers contacting us with the same question “ why isn’t my air con cold?” Having your air-conditioning blowing out warm air or simply not working is annoying, especially in a heatwave!

Thankfully though,  getting air con back to being icy-cold & fresh is usually quick & fairly straightforward.  However there are a few reasons why it may have lost it’s cool.

Why is my air con blowing warm air?

There could be a number of reasons why your air con may be blowing out hot air. Over time, vehicle air conditioning systems can lose efficiency due to refrigerant leaks, clogged filters, and worn out seals. However the the main and most likely reason for your AC not working is that the AC system is low on refrigerant.

It could be low beacuse:

  • It’s ready for an air con regas
  • The AC system has a leak

Refrigerant is a special type of gas that has been compressed into liquid which gives the unit its cooling ability. When this is low the AC system doesn’t have enough power to function.

When your refrigerant is low you need to book your vehicle in for an air con “regas” or “recharge”. Air conditioning regasing involves evacuating the refrigerant gas from your air conditioning, testing for leakages, then re-filling and pressurising the system.

Most manufacturers recommend an AC regas every 1-2 years so it’s advisable to think of servicing your air-conditioning system in a similar way to servicing your vehicle.

• Most vehicle need an AC regas every 1-2 years
• Low refrigerant is the most common reason for AC not working
• An AC regas removes old gas, tests for leaks then refils & pressurises the system

How does vehicle air con work?

Your vehicle’s AC system is made up of five key components:

  • Compressor
  • Condensor
  • Expansion valve
  • Receiver
  • Evaporator

So here’s what actually happens when you switch your air-con on!

  1. Inside the air conditioning system is a compressor, which is where the refrigerant is stored.
  2. When the air con is switched on, the gas travels to a condenser. Fresh air from outside the vehicle then passes over the condenser and cools the gas down. This is when the gas liquefies.
  3. Once a liquid, a drier removes any impurities from the liquid before it reaches the thermal expansion valve. This is what allows the driver to control the temperature by limiting the flow of liquid.
  4. Lastly, this liquid is turned into vapour as it travels through the evaporation coils and is blown into the vehicle as cool air.
  5. Now back as a gas, the refrigerant then returns to the compressor to start the process again.

Why does air con need gas?

Your air con system has multiple components, but it is the refrigerant that is key to the smooth running of the system. The refrigerant helps create the cool air and without it, the system would not operate. It is a crucial component for a working system as it absorbs heat from the environment and converts it into a cool air flow when combined with the other components of the AC.

If your air conditioning system is low on refrigerant it will be far less efficient and will have to work much harder, putting a strain on your engine and use more fuel.

You are also likely to see a significant decline in the performance of the system as well as noticing an increase in the amount of time it takes to demist your windscreen in the winter months.

If your air-con runs out of gas completely it simply won’t operate and you may hear an echoing sound coming through the vents as it struggles to work. The compressor would shut down in order to prevent further severe damage taking place. 

What air con regas does my car need?

There are two different types of air conditioning regas services available to book. Which air-con regas you need will depend on the age of your vehicle and which gas it’s AC system needs.

The two different AC refrigerants or “gases” used are:

• R134A which is the standard recharge gas
• R1234YF which is the new generation recharging gas

R134A is for vehicles made before 2017

The standard R134A is used for vehicles made before 2017 has been used for over 20 years. However, in recent year it’s been found to be extremely damaging for the environment and a contributing factor in the destruction of the ozone layer.

Although we can still use this gas on older AC systems, we have to take measures to help reduce any damage. All our air-con technicians are F-gas registered & fully trained to prevent the R134A gas escaping into the atmosphere during the regassing process. It’s for this reason that a nitrogen test is carried out prior to a recharge on any system that contains no gas or that we suspect may have a leak.

R1234YF is for newer vehicles from 2017

All vehicles manufactured after 2017 (& a few models prior) have AC systems that require the new R1234YF gas to operate.

This gas has been introduced for new vehicles as it is far less damaging to the ozone layer. Unfortunately it is more expensive to purchase but is the only gas suitable for cars manufactured after 2017. We offer the R1234YF air-con regas in a number of our branches which can be booked online at the cost of £99.95.

How can I maintain my vehicle AC?

Regular maintenance is incredibly important when it comes to keeping your car’s air conditioning system in good health. So many drivers completely forget about their AC during the colder months. Using it throughout the year really does help ensure it stays in good working order and alerts you to any potential problems before a heatwave arrives and you desperately need it.

A few ways you can keep the AC system in good working order are:

  • Run your car air conditioning once a week. This is especially important in winter as regularly running your air conditioning will maintain your refrigerant gas pressure. Once summer comes along, your air conditioning will be better prepared for those hot summer days.
  • Use your AC to demist your windows throughout the year. Not only does this keep the system in good working order, it also works more quickly to clear your windscreen than a heater in cold weather.
  • Use your vehicle air-recirculation button in hot weather. This will cool your cabin down more quickly and put less strain on your air-conditioning system.
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