As an aside form this subject, would'nt disconnecting the belt to the compressor save some HP? As I have said before, I do not run my AC. I would think the engine turning that compressor constantly has got to add some resistance. Thanks for all the input also. I think if I ever do get to my airconditioning, the first thing would be a conversion. They are making old freon to expensive, especially with systems prone to leaking like 911's. Michael

Had the same queston Michael and posed it to one of the members in our club w/ the same 911 as ours. There is a clutch in the compressor that engagaes only when the air is "on". Therefore the drag when the air is off is negligable.
I'm beginning to think the answer is convert to 134 w/ the new bolt in pump "KIeffert". Spelling is way off but this thread will probably get us there. The people who sell it advertise in Pando. Seems no matter which way you go(except removal) will end up between $1-2,000. Cans of 134 are legal and cheap. Better deal in the long run if you don't go to a 993.
Soon,
Willie 88

FYI-for some that might be wondering. If you compress a gas (your compressor)into a confined space (your line)it gets hot. If you take the heat energy away that was caused by compression by letting the confined space cool down (your condensor) you still have a compressed gas that is no longer hot but has pressure. As you slowly release the pressure (small pinhole or expansion valve) the gas expands and the gas gets colder (your evaporator)now all the pressure is gone and after it goes through the drier (Filter for moisture and contam.) it is sucked back in to the compressor to start it all over again..

During the part where the evaporator is cold (it looks like a radiator) a separate fan blows ambient air through it which cools the air and it is the air that shows up in the cabin as the "cold" air that blows from the vents. Over simplification maybe.

The more efficient any part in the system is (ditching the york for a sanden or adding more condessor area etc.) the better the system will work. The compressors is controlled by a high pressure sw.that cuts it off when the high pressure is reached. (it will turn longer at idle then at 3000). Lastly the r134 is less efficent then r12 and uses different seals and compressor oil but still cools fine. Just change the oil in the comp and use barrier hoses if you can.

Sorry it went long, hope it helps someone.

s