My PC has physical switches that control the top and front fans. They were working normally yesterday, but today both fans run on the LOW setting and stop completely when I switch them to HIGH, as if they were turned off. What could cause this, and how can I troubleshoot it?
2 Answers
Since both fans fail on the HIGH setting at the same time, the controller or its wiring is more likely the problem than the fans themselves. Shut the PC down and unplug it, then reseat the controller’s SATA or Molex power connection, try another power plug from the supply, and make sure the fan connectors and switch wires are firmly attached. You can also disconnect one fan from the controller and connect it directly to a motherboard fan header; if it runs properly there, the controller or switch is faulty.
Older physical fan switches can develop dirty or worn contacts, so one position may stop making a proper connection. With the computer powered off, move the switch between LOW and HIGH several times and inspect the wiring for a loose connection. If reseating the cables and testing the fans directly does not help, the fan controller or the switches may need to be replaced.
Thanks for the suggestions. I tried checking the connections, but the fans still stop whenever I select HIGH, so I’m starting to suspect the controller or switches themselves.