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78 Living the Legend – 911 owner reports
Living the
Our contributing enthusiasts from
around the world share their real-life
experiences with their Porsche 911s
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 from the vents.
While I’m still not tempted to drive the
car when it is 46°C outside, it is now
quite comfortable into the mid-30s.
Over the years I have found that the
rate of hose permeation has dropped,
with only a minor top-up required each
year. I’m not aware of the availability
of hydrocarbon refrigerants in other
countries, but they certainly provided the
solution I was looking for.