Lets face it, R134A is rubbish when it comes to cooling older cars. It is significantly less efficient than R12. Systems that are not designed for it struggle to keep the car tepid in the Australian summer.
Added to that, the air conditioning on the 107 models from Mercedes was never their strong point either, so when you couple a marginal system, that is now 40 years old and a less efficient refrigerant, you’re not going to get a good outcome.
If this is all meaningless to you, it refers to the refrigerant found in automotive air conditioning units. Up until the 90s, cars used R12. R12 was later found to be bad for the environment, so was replaced with R134a, which is not as bad for the environment, but far less efficient. New cars upgraded various components to get the same level of cooling, but older cars were retrofitted with R134a had to make do with what the had.
I started doing some research on alternatives, and on the ozbenz forum, there were a few members who had converted to HyChill with good results, including one who recommended a place near me who was doing the recharge. I took the SLC in, and the result was good – much cooler A/C. It’s not as good as the setup on a modern car, but it keeps the car pretty cool. Good AC makes the SLC a much nicer car to drive in summer. The one thing I did find, was that the refrigerant is a bit more flammable than R134a. I am not worried as a very small amount is used. Anyone wanting to do the conversion will have to weigh that up.
Update 2018: The shop near me that used to do the HyChill regassing no longer do. I now have a new compressor in the 450SLC which copes with R134A better than the old one did. I imagine HyChill would be better, but I don’t have a source anymore.
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