How To Check An A/C System Works.


So you're off to see that new car you want to buy and obviously you are excited. There are so many things to check though - bodywork, tyres, clutch, service history ... but don't forget to test the air conditioning is working too! If the car is being sold privately then once you hand over your money and drive away you have no legal rights and if you notice the A/C isn't cold on the next sunny day you could have a large bill in store.

While on your test drive turn the A/C to maximum and put the system in "recirculate" mode (assuming there is one) - it's usually a button with an arrow bent back on itself. Within a minute or two the air from the vents should be noticeably chilly. If you have a digital thermometer at home - perhaps in the kitchen then bring that along and you should be able to measure the temperature of the air coming from the vents. The temperature should be around 6° C.

Whilst you are having a look under the bonnet you can also check if the air conditioning compressor is working. With the engine running and the A/C set as above listen for a clicking noise accompanied by the engine revs rising or falling slightly. This is the compressor engaging and disengaging and is what you want to hear. You may need to turn the A/C on and off to make this occur on demand.

Lastly if you know a little about cars look for the metal air conditioning pipes. You should be able to locate a thick pipe (low pressure) and a thinner pipe which is the high pressure side. When the A/C has been running for a couple of minutes the thicker pipe should be nice and chilled - almost frosty to the touch. Be careful when putting your hands into the engine bay with the engine running as you don't want to burn yourself or put your fingers into a spinning fan!

Enjoy your new car and remember to Stay Cool!