"They come in threes!" I was gleefully informed, after the car exhaust needed replacing, and then the MOT. True enough the third day that I chose to use the car, number three did arrive. The weather was horrible, I'd been cycling for weeks, and needed a break. Fortunately this appeared to be fairly minor, expense-wise.

The blower fan stopped working in all but the "max" setting. No gradual change, of dropping from four speeds to three, then two. Just straight to Off/On control. The culprit's in there, and, not getting big-headed about it, was exactly what I suspected.

This part is positioned (the other way up) in the air flow, to keep it cool. Each of those coils of wire are resistors of differing values. They're individually selected to restrict the current to the motor, when you click the switch to a position other than "Max". That other little cylinder with the red cap, was the suspect. Whatever low speed you select, the motor's current has to pass through it. So if it goes, all the lower speeds stop working. I figured out that one may be fitted.

It's a thermal fuse. If things become too hot, for example, if the fan seizes-up, the heat from the resistors will cause the fuse to blow. Hopefully saving any other potential damage, or even a fire.

Most garages would replace this as a unit, at a minimum cost of £25 (more likely £40+)... just for the part. It took a while to find out exactly where the thing was located; how to get at it; and then actually remove it. The Internet community gave a large variety of misleading information!

Have ordered a replacement fuse. A pack of five is £2.15! That's from an electronics supplier, not a garage...


Cautionary note: Be wary of working on modern vehicle electrical circuits. You could very easily trigger various (dangerous!) safety features, such as air-bags, or seatbelt tensioners. Always RTM (read the manual), it may require you to: disconnect the battery; wait 5, or even 15 minutes, before commencing any work.