Why an air-con re-gas may not work

Posted on August 4th, 2015 by Rob Marshall


Why an air conditioning re-gas may not work

Several hot spells this summer have led many motorists to discover that their air conditioning is simply not up to the job. In most cases, the cause is down to refrigerant gas leaking from the system, through either a fault, or natural wastage.

Unsurprisingly, one of the country’s better known fast-fit organisations has reported that it carried out three times more air conditioning re-gasses in the first week of July, compared with the preceding seven days. Yet, in some cases, re-gassing can only restore the air conditioning system temporarily and this issue reached the mainstream attention of Jeremy Vine, in his radio slot that was also broadcast in early July, in which listeners were invited to call in and share their experiences of having their air conditioning systems failing, within a short period of having it replenished.

My experience with fast-fit centres generally is that they do not have a dedicated air conditioning specialist in each branch. Mostly, each centre is equipped with a sophisticated machine and the operatives are trained to use it, instead of understanding the exact way in which it works. I think that this is a major reason why air conditioning systems fail within a short period of being re-gassed, because a machine is relied upon, in-lieu of dedicated human knowledge and experience.

As it is not legal to re-gas a leaking automotive air conditioning system (because the refrigerant is harmful to the environment), the machine tests the circuit, by applying a vacuum. If the system appears to be stable after a set period, the re-gas can proceed. However, this method can hide certain leaks, especially in rubber pipes, because holes can be inverted, thus giving the false impression of the whole circuit being leak-free, but the issue becomes apparent when it is pressurised with refrigerant subsequently.

I had personal experience of this several years ago, when my car was vacuum tested and regassed at a fast-fit outlet, before failing after two days. I consulted a dedicated air conditioning specialist, who pressure-checked my car’s system with nitrogen gas, which does not damage the environment. The immediate sound of escaping gas from the front of the engine verified that a leak was very much apparent, which was not picked-up by the fancy machine.

Therefore, apart from following GEM’s top tips to keep your air conditioning system in fine health, should you discover that the system does not work, I advise that you spend your cash with a qualified air conditioning professional, rather than with an outfit that has bought a fancy machine. Sadly, there is no automotive air conditioning professional body in the UK but this link should help you find your nearest expert.