1980 Mercedes 300SD A/C & Heater Blower problems. Help?

[sfk]

The Blower does not work untill the car warms up and get pretty hot. Then when I put the A/C on, the blower goes on.
After days of this problem, now when I put the A/C on, the Blower went on but the air is not cold.
I am suspecting either the blower is working intermitently. I think the temperature gauge is working ok.

ANY thoughts??