One other test youcan do it's a bit dangerous to do with tje car running tho. Win the A/c on and 12v to the clutch you can try taping or pushing the front of the clutch in and see if it engages you will hear an audible click from the compressor if it does.
This is not volvo 240 specific but over time the clutch face and the compressor face wear and the air gap between the two faces is to big for the electro magnetic clutch to engage.
If ypu help it and push it together and it grabs you know its the clutch and depending on the model I know some sanden compressor have removable shims to adjust the air gap behind the clutch plate. If so you could remove 1 or 2 shims to shrink the air gap.
But before you remove the clutch just try to above test.