Solve intermittent Bluetooth problems on the Mac Mini

Over the past few months my Mac Mini keeps losing connection to the Bluetooth devices (namely my keyboard and mouse). After a while, it will reconnect, and then eventually lose it again. The duration it loses connection for increases and increases, until eventually it doesn’t pick up the Bluetooth devices at all. I found the only way to make Bluetooth work again was to unplug the Mac Mini from the power at the back and leave it for about an hour.

After some Goggling, I found I wasn’t the only one with this problem, but nobody had come up with a fix yet for the broken Bluetooth. I started leaving a cabled USB mouse plugged in as well as my Bluetooth mouse, so when it happened again I could have a dig around to investigate, and then I discovered that it wasn’t the devices losing connection, it was the Bluetooth hardware itself failing. The status icon by the clock was changing to the Bluetooth logo with a tilde (~) through it, and the status was “Unavailable”.

The thought then occurred to me, with the durations getting longer, and only getting warmer as we head into Summer, that this could be heat related. I downloaded a program called Temperature Monitor which places a temperature gauge up by the clock. I set this to run on start up, and kept going for a few days. I noticed, that the Bluetooth turned off as soon as this was reaching around 53 C ambient temp on the north-bridge. I thought it was a little odd, that a computer would get this hot and I couldn’t hear a fan spinning, and upon investigation, it wasn’t spinning very fast at all!

To cure this, I downloaded a program called smcFanControl with the aim of tweaking the fan settings, and discovered that the fan was set ridiculously low by default. I turned it up from 1500 RPM to 3350 RPM, and immediately the temperature dropped, and the Bluetooth turned back on! Success!

So there you go: to fix the Bluetooth on a Mac Mini from cutting out, download smcFanControl and turn your fan up a bit.