Got an 02 plate facelift series 2

Has the TD5 engine

the air con pulley squeaks in use...doesn't do it all the time and is more noticeable when cold...if you switch air con off it shuts up...

sounds like the bearing in the pulley has got...

can you replace these or if not would removing the bearing and soaking in oil stop the squeak...

how do you remove them...

many thanks...