968 Fan Cycling Cured!!
My Porsche dealer couldn’t figure it out but I did: I can say that the 5-7 second fan cycling was caused by a bad connection to the ceramic fan speed resistors on the firewall by the battery under the weather cover directly behind the RH AC pollen filter in my ‘94 968. The default mode for the fans is to cycle from low to high every 5-7 seconds when there is an open circuit. While the connections looked fine at first, the top wire under the insulation and connection was only as thick as a human hair and the ceramic disc had cracked on the back side. I ordered two new ceramic resistors from my Porsche dealership and soldered a new connector to the frayed wire. Now my fans behave as they should and the higher speed fan only comes in when needed (AC running and engine temp at 1/2 mark or AC off and temp at about the 66% mark on the gauge). No more cycling on and off every 5-7 seconds. No more hearing the relay click on and off every 5-7 seconds! That was driving me crazy for weeks. And it really helps with car’s battery life. Hope this helps!