This is a problem that is almost impossible to diagose over the internet.
Any of the idler brgs, fan pulley bracket, water pump brgs., alternater brgs., or A/C compressor clutch brgs. could make a "whining" sound. An expert MB tech needs to look at the car now that the noise is worse, and possibly remove the belt to be able to freely rotate the pulleys and check for a bad brg.
14 year MB tech
7 year shop foreman @ independent MB/Volvo shop
[This message has been edited by MB Medic (edited 04-10-99).]