It's probably the controller located in the dash behind the radio. It's a little box, actually there are 2 or 3. They start clicking because the switch it motor in them screws up. They direct the air from upper to lower.
Chevy runs deep, don't step in Chevy.
chevy runs deep, Don't step in chevy!
67 Coupe 289 - TCI C4 w/2k stall; Holley 4150 570cfm; Performer intake; mild cam; Pertronix HEI; 302 heads; Roller Tips; Hedman Tri-Y headers; H-pipe w/Flowmaster 40's; 9 in posi 3.50; 205/50-17F; 225/50-17R.