Air recirculation not working...

[trophy425]

... pressing the button does nothing. This was fine until recently when it worked once and switched to recirculate and has subsequently stopped working again; so the windows are always steaming up now; question is, i reckon the motor in the servo has blown and needs replacing but where the hell is it? And anybody know how to get at it to replace the unit? (Please don't tell me the dash needs removing)

 

[trophy425]

Maybe should add it's the normal air con fitted, not the full climate control.