AIR CONDITIONING BLOWS BUT NOT COLD

Sooo, just tried the air con in my new secondhand SC 1993 turbo diesel. Blowing well but NO cold air. I spoke to a mechanic who wants to just look at it before I go spending money on a special gas(?) for it (being a 93) and I said, "isn';t it just regassing" and he said, "How often do you regas your fridge?" SmartA. I HAVE had to regas my 2003 Huyndai twice since I bought it. I'd appreciate opinions please - we leave to go on a short trip on Tuesday (typically Sydney going to have a heatwave, Murphy's Law for me). We did survive yesterday by opening the second roof, that big one, felt nice on the back of my neck BUT any advice appreciated. Also, if anyone knows anyone in Melbourne that DOES this sort of thing for the SCs please advise.

In Brisbane I've had good service from Natrad. Being a franchise, you can probably find one in Melbourne.

I had mine done at natrad moorabin now blows nice and icey

Mine was the same. The PO didn't care about having it functional.
The shop that did my conversion was hesitant but all went well. There was still pressure in the system which was the main reason he went forward. The fans didn't turn on due to the low pressure, who knows how long it had been since it was used.
Made it through the summer without a problem.