does a/c draw power always or only while on
 

I definitely feel the diff when it's on but does it always draw power?thanks

Pat

Only when it's on. When it's off, the belt is not spinning the compressor, so drag would be almost nothing at all.

Just as Jim said, you are only spinning the compressor when the A/C is on. However, there is still some parasitic drag on the crank from the clutch and belt (especially if the belt is too tight). So as a semi-solution, I have removed the belt completely. My car is a Targa though, so even in the summer I don't use A/C. Not to mention, 911 A/C performance is usually marginal at best anyway. I have often thought about removing the entire A/C system (as I have done on a previous 911), but I didn't want to hassle with that again, and I didn't want to negatively affect the resale value. One caveat though, With any A/C system, you should periodically turn it on and let it run for a while to keep everything in good working order. So, if you remove the belt, you aren't able to do that.

thanks- thats what I thought but wasn't sure as I have heard different from different people

pat

I have done two AC removals. In my own 89, I took out the condensor and disconnected the hoses and tied them back. The amount of draw on the engine without the condensor on is very slight and not Hp sapping. The throttle assemble has a full acceleration sensor that actually shuts off the compressor. I just did it because my AC never worked and I was looking to clean up the engine bay. On an 87 coupe, we removed the entire system. It wasn't hard to do because we were rebuilding the car for track racing and it was mostly emptied out. To do this just to remove the AC is a lot of work for mostly minimal gains. There are dozens of littly holes under the body from the hose clamps that will need to be filled. Since we are repainting the body and having body work done, it is not a big deal. The entire system weighs less then 75lbs. Since my 89 is mint, I couldn't see going through all this. To sum it up: If your doing major changeovers in your car, why not. If removing the AC is the only issue and your car is very nice, it is not worth it.