Living the Legend
Peter Wilson
Adelaide, Australia
Model 930 3.3
Year 1980
Acquired 2011
Summer is nearly here in South Australia, and in preparation I have just done my annual air conditioning service as Adelaide can get pretty warm – last summer we had a 46°C day! While classic Porsche 911s have many fantastic attributes, air conditioning is not one of them, as the system was cobbled up and shoehorned into a chassis never designed for it. The main condenser in a 930 lives in the ‘tea tray’ spoiler and when the car is stationary only has the engine cooling fan to pull air through it. The puny secondary condenser is under the trunk and has no air inlet, while the evaporator on a RHD car lives under the passenger floorboard and is trying to suck air though the carpet! Linking all these components are metres of permeable flexible hoses, slowly leaking the refrigerant charge. Not Porsche’s finest hour…
At some point in history, my car had been ‘converted’ from R12 to R134a when CFC refrigerants became illegal due to their environmental impact. Unfortunately the conversion simply consisted of replacing the fill port connectors and swapping the gas and oil, actually even further degrading the system performance as R134a is an inferior refrigerant.
Refrigerants in Australia are highly regulated and R134a cannot be sold to the public here. I was trapped with a pathetic aircon system and paying a fortune to have it recharged every summer. While there are a number of redesigned aircon components and systems made in the US, I was keen to improve on the situation and keep the system basically original.
My salvation came in the form of hydrocarbon refrigerants. HyChill are an Australian manufacturer and their recommended refrigerant for automotive systems is called HyChill Minus 30, which is a blend of R600a (isobutane) and R290 (propane). Even better, I can buy it in a 9kg cylinder which gives me dozens of recharges, it’s a better refrigerant than R134a, it’s compatible with existing aircon lubricants and is environmentally friendly.
The only possible concern is of course the flammability of the hydrocarbon refrigerant. I did a lot of reading about this and satisfied myself that the risk of a major leak was low, that I would smell it and that I don’t smoke. In a crash situation, I’m not too worried about half a kilo of hydrocarbons when I have 80 litres of 98 octane at my feet…
So about three years ago I had the remaining old R134a charge recovered by a refrigeration mechanic and was then free to evacuate, leak test and refill my own system with Minus 30. The vacuum pump and gauge set cost me a little over $100, and I hooked up a temporary fan on the main condenser to enable the aircon to be operated with the engine cover open.
As I didn’t know the original charge weight, I recharged based on pressure and simply introduced the Minus 30 refrigerant slowly to the low-pressure side of the compressor until the desired low and high side pressures were achieved. Immediately the system performed better than it ever had with R134a, with nice chilly air
