Try a new switch
Try useing a switch that can handle higher voltage. I had the same problem until I switched to I believe a 25volt switch and then everything worked fine. If I remember right mine was making a clicking noise and then the fan would stop working. Good luck.
94 GT, Vortech S-Trim, AFR 165's, BBK Longtubes, Edelbrock RPM Intake, Stock cam.
RWHP 388.1, RWTQ386.1 1.96 60' 12.57 @113.53 MPH