Welcome to the first in a series of How-to guides. Unlike most of the geeky articles I write, these will be about car related DIY, which is a small hobby of mine. This first one comes about because I was looking on the internet for information about the Fiesta Mk7 (2008-2017) A/C system, but there was nothing useful out there.

Ever noticed that your air conditioning is a bit slow to cool down, or maybe it isn’t as cold as it once was? The chances are that you have a slight leak in the system, and some of the refrigerant has escaped. The main reason for this is lack of use. The refrigerant contains lubricating oils that keeps the seals supple and working. If the refrigerant isn’t kept moving through the pipes from time to time then there is chance for the seals to dry out and shrink slightly, which is how you get the leaks.

The easiest way to avoid this is to run the system for about 10 minutes or so, at least once a week, even in winter. Some people recommend leaving it on all the time, but that seems unnecessary to me, as well as a waste of fuel and a drain on the car’s power.

If your A/C doesn’t get cold at all then this guide probably won’t help, your system may need repair, or at the very least completely refilling by a professional. The same applies if it won’t switch on. If when you turn the A/C on you hear a click but no change in engine note then it means the compressor isn’t working properly. If your system is working but not very effectively, read on…

A word of warning. Hot engines, compressed gas and moving parts can all cause injury or damage. Follow these instructions at your own risk, and if in any doubt consult a professional technician.

First you will need a can of DIY refrigerant like this one. When I got mine (many years ago) it came with the necessary filling hose attached. These seem to be rare/expensive nowadays, so you may also need one of these hoses that screw onto the aerosol. Have a good look at the connector you’re getting, and try and get one with a 90 degree connector, rather than a straight one. The reason for this is that the pipe you need to plug into is located very close to the panel above it, and is difficult (but not impossible) to connect to with a straight fitting.

Once you’ve got your can of refrigerant/sealer/oil mixture and attached the hose you will need to get the stuff into your A/C system. Open the bonnet of the car and you will find the Low Pressure Service Point just below the rear edge of the bonnet. The car shown is a 1.6 TDCi, other engines may have the fill point in slightly different positions.

Here is the connection point close up, it’s located immediately behind the brake fluid reservoir. The service point is protected by a black screw on cap.

Remove the black dust cap from the service point, then carefully connect the filling hose to it. You need to lift the collar on the connector, slide it over the service point then release the collar. It can be quite fiddly, as space is limited. Once connected make sure that the can is in a safe place, or get someone to hold it, as you now need to start the engine, open the windows and switch on the A/C or climate control. Set the temperature to the minimum. Once the compressor is running you can gradually add the refrigerant. You should hear the engine note change as the compressor clicks on and off.  If there is any sign of leak, such as a hissing sound from the pipework, then stop immediately and refer the system to a professional for repair.

Now that you’ve added some refrigerant you should very soon notice an improvement in your A/C system.