378 Aircon recharge on an RV8 After 16 years good use his with ex Japan 1996 RV8, David Allen found the air conditioning system failed to produce cool air. Here he explains how he found a convenient way to have the system checked and recharged. (June 13) The RV8NOTES don’t seem to have anything on this specific issue so I phoned around for companies who could do a check of the system and refill with refrigerant if that was the problem. I hoped for nothing worse! There are several companies offering this service and after talking to all of them I chose Kwik Fit, the chain of workshops in the UK who do replacement tyres and batteries and now aircon services. I found Kwik Fit who do the aircon job at several, but not all of their branches. I went to Kwik Fit in Peterborough and they did the job in one hour for a standard price, £49 - and provided excellent service. The system was drained down and then put on a permanent vacuum for 10 minutes to check the seals. When this showed the system was tight they refilled and checked the operation of the system as well as explaining to me what they had checked and what had been done. They also advised me to run the system regularly for short periods even in the winter, to keep the seals lubricated. The mechanics were courteous, technically competent and with a good customer approach. I could not recommend them more highly to any RV8 owner wanting a similar job done. I had cool air all the way to MGLive! on a muggy day with the hood up! See the Kwik Fit website for details of their aircon services. More Locate a Kwik Fit branch near you that does aircon servicing. More See our illustrated version of this note. More Safety cut-out switch on the high pressure circuit of the aircon lines A few weeks after David Allen's report on his experience with recharging his aircon system, a V8BB thread launched by Peter Wallis reported his aircon had failed to run and he sought help with understanding the function of the automatic cut-out. Our auto aircon expert Geoff Insley was able to provide a useful explanation of how the cut-out switch works. The V8BB posting from Peter Wallis was during a period of very hot weather in the UK and he noted "like many of you I've been using the RV8 in these wonderful conditions only to find that my aircon would not switch on, so in passing an original MG garage 'Beech Hill' near Reading I asked them to take a look. The result is the RV8 will be going in for an aircon service." He then added " I've heard before that within the aircon circuit there is an automatic cut out that prevents the aircon running when totally empty so we shall see what Beech Hill find. I was wondering if other RV8 owner's had experienced a similar problem? Also on the bulkhead to the right of the brake servo there is an aircon control box, it's also worth checking the fuses in there." Geoff Insley provided a clear explanation: There is indeed a safety cut out switch on the high pressure circuit of the aircon lines, fitted to the receiver/drier - see the diagram of an auto aircon system on the previous page. It's called a trinary switch as it has three functions: 1. To turn off the system if the pressure goes below 2 bar (normally through loss of refrigerant). 2. To turn off the system if the pressure goes very high, about 25bar or more. This can happen in extreme conditions if the condenser fan fails or if there is a blockage in the system. Auto aircon system diagram. (Source: Geoff Insley) 3. To operate the condenser/radiator fan independently of engine temperature when the airflow through the condenser is too low, normally in traffic. This happens at about 18 bar. It functions by interrupting the electrical supply to the magnetic clutch on the compressor, protecting the compressor in the case of loss of gas (it will lose its lubrication), and protecting the system from a possible pipe or joint burst in the case of over-pressure. If Peter's loss of gas is due to a leak, the garage should find this on pressure testing the system before refilling with refrigerant, but if it has been open to atmosphere for any length of time it's a good idea to replace the receiver/drier, as the dessicant inside will be saturated. The function of this is to remove any remaining moisture after the system has been evacuated prior to refilling. Moisture will cause corrosion inside the system leading to further failures. Copyright reserved by the V8 Register - MG Car Club