quote:I've bought a 73 Pantera last autumn, with A/C that doesn't work. I know the system needs filling, but is that all? When I drive and turn the A/C knob, nothing happens. I would imagene that if the system worked but was empty, the compressor would cycle on and off, but I'm pretty sure it doesn't.
What do I do, fill it up, risking it's a waste of money?
First off, congratulations on your purchase!
Stock system uses R12, which is a better refrigerant than R134. I would not do a conversion for this reason. Your hoses are probably original, and may need replacing which means $$$.
Likewise, your compressor, if still the original York, may have bad seals and need repair/replacement = $$$ These can be replaced by a Sanden 508 with R12 fittings at a cost of about $200-$300.
Your drier should be replaced, too. Probably well used up by now = $50
Yes, turning on the AC rotary switch should flip on the compressor AND the fan mounted on the condensor.
I'd go to a shop that is good at AC work and have them first pressure test the sysem for leaks and bad seals/fittings. I think they can do this with nitrogen. Once that is proven/fixed, and that may involve everything listed above, go ahead and fill her up with the $$$$ R12 - costs about $50 a pound here in the states through a shop. You'll need about 3-4 pounds for the system to work well.
Not a cheap system to fix - I paid a shop about $900 last year to get mine up to spec - but sure makes driving a lot nicer in the warm summer.
Larry