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Air Conditioning Servicing - Service Insights with Peter

Posted in Servicing 4 years ago


When it comes to air conditioning maintenance, depending on the service interval we would recommend that your system is either regassed or serviced. Although a much-overlooked aspect of vehicle servicing, diligent A/C maintenance is essential to avoid expensive repairs.

Typically, your A/C system loses 10-15% of its gas charge per year. Therefore, over a two-year period its feasible that your A/C system could have lost almost a third of its recommended charge. The oil that lubricates the system is suspended in the refrigerant, so loss of gas results in loss of lubrication in the system, we will recommend that the system is evacuated and regassed - see details below.


At a 2-year interval we recommend that you A/C system is regassed, with the basic process as follows:

Carry out visual check of system. Check for evidence of leaks with UV light. Run system and note vent temps, we like to see cooling temp of 3 - 8 C at vents. Recover gas. Note amount recovered.

The gas is now so expensive that we charge by the gram instead of charge weight, so if we remove 500g of gas and the system charge is 600g, you only get charged for the difference.

It’s very rare that cars are with us for only one day, that gives us the opportunity to pressurize the system with oxygen free nitrogen overnight and check that the system holds pressure over that period. The nitrogen also has a flushing effect when released from the system. The system is then held in a vacuum which boils off moisture. The vacuum is typically held for 20 minutes, but we specify a period of 45 mins to 1 hr, which leads to cooler vent temps. The system is then recharged with the correct charge weight of gas and oil. We tend not to add additional UV dye. By the time cars have been in service for a good few years, everyone adds dye anytime the system is worked on and it ends up saturated with dye.

We will then run and verify correct operation of the system and retake the vent temps.


For the 4-year interval, we recommend that the A/C system receives a full service. This includes all the above items and process, but also includes the replacement of the receiver/drier bottle, which is essentially the filter for the system.

A couple of further points that are worth making are that firstly, this schedule assumes we have been looking after your car under our maintenance schedule and have all service history to hand. Secondly, most manufacturers of A/C components recommend this filter is changed at a two-year interval, however we are comfortable changing it on a four-year cycle. This means that if we are seeing your vehicle for the first time, we are highly likely to recommend this service.

Air conditioning maintenance is best carried out in conjunction with an annual service as access to the drier bottle involves removing vehicle undertrays on certain vehicles and meaning that labour time can be minimised.  

The drier bottle performs several functions which are crucial to the performance of the A/C system and if this is left unattended for too long, it can lead to extremely hefty bills to restore the function of the entire system. After studying patterns of gas loss on vehicles, we also replace the high and low charge ports during this service as we have found they are a major source of low volume, hard to detect gas loss.


Although we have the equipment to clean and relieve odours in a car’s A/C system, we don’t find it to be a big issue amongst out clients. It’s something to be aware of if you have family members who are susceptible to air born allergies. The air con service does include a cabin /vent freshener which will deal with any minor odours.


A/C on Heritage vehicles tends to fall in to two categories - either the car does not have A/C and you would like a system fitted or the vehicle has an A/C system that has seen better days and requires refreshing or replacement. Based on individual enquiries we are formulate a cost for the best course of action.