Hi,
The new front bearing needs to be pressed on and the old one pressed off. So, the crankshaft has to be out of the compressor. To get the crank out you have to unbolt the piston rods from the crank and to get to those you have to remove the oil sump pan. Removing that sump pan is impossible with the compressor mounted on the engine. Long story short, there is no way to do it on the engine I can think of. Along with a new bearing you'll need a sump gasket and front seal kit, which is a seal and big O ring.
