Nicky

You wouldn't necessarily need to remove the compressor as when it's not switched on it doesn't take any load from the engine and basically acts as another idler pulley. Alright, so there would be some small loss due to the belt driving one unnecessary pulley, but it would be negligible. As for removing the radiator though, well, that's a whole other kettle of fish, as Jason said involving some unpleasant gases....