1979 300sd ticking noise under hood
 

My 1979 300sd periodically makes a ticking / clicking sound when the key is in the on position (pre glow) and not running. I think it is something from the HVAC system?? I don't know if this would have anything to do with it, but when I purchased the car last week, the blower didn't work and nothing worked for the HVAC system. I replaced the fuses and got the defroster button to work for heat. The other buttons also work but melted the AC fuse.