Cooling fans causing electrical noise, need help

[Radioflyer97 10+ year member]

I'm experiencing significant electrical noise from my amp rack’s cooling fans. The addition of a relay setup only made it worse. Here are a few details of my setup:

I’m currently running the fan power switch from the amp’s turn-on-lead to a 5v power regulator to the Stinger SFC temp switch. (seen here) The fans run at half power when the amps are on and 100% above 90 degrees.

http://cgi.ebay.com/STINGER-AUTOMATIC-FAN-CONTROLLER-SFC-4-AMP-FAN-SF3N-NEW_W0QQitemZ310035025651QQihZ021QQcategoryZ14932QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Ground is separate from the amplifiers.

How can I get rid of the noise?

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