I’ve noticed over the last few months that upon start up there’s a noticeable ‘buzzing’ sound emanating from the right side of the instrument binnacle; it had got markedly worse over the last day or two. I assumed it was a dodgy relay or something similar as it sounded very much like a relay energising only very loudly. I had a quick look but couldn’t find anything obvious so I posed the question on the Discovery II forum, sure enough five minutes later there were a couple of suggestions as to the likely culprit, chief among them was the small fan on the in car temperature sensor (ICTS). A quick look confirmed it was indeed the fan on the ICTS (part number JTF100290). The cause appears to be over time, dust, fluff and general crud get drawn in by the fan causing it to operate noisily. The ‘inlet’ for the fan of the ICTS is located by the driver’s right knee (RHD), it’s a little, horizontal slatted grill to the left of the headlamp levelling switch (if fitted).
It can be cleaned in-situ, but for a thorough clean it’s best to remove the unit completely; this is easier said than done… If like me you’re not blessed with dainty little hands, access to the fixing screws can best be described as awkward! In the next picture you’ll see the unit in place with the lower fixing screw arrowed, the upper fixing screw is diagonally opposite this. For ‘easier’ access it’s best to remove the plug to the rear of the headlamp levelling switch and also the plug to the ICTS itself. Tuck these out of the way to create a little space to work in. Once you’ve removed the two fixing screws take the unit somewhere you can work on it, I chose the footwell, probably not the wisest choice in all honesty!
Once the unit is removed, carefully remove the two small bolts, washers and nut holding the two halves of the unit together. Be very careful at this point as the nuts are not captive and will inevitably fall out and lose themselves if you’re not careful. The lower fixing also has a small bracket that holds the wiring loom to the unit. See the next picture in the sequence.
*Be VERY careful at this point as the unit, once opened is very delicate*
With the unit in two, carefully brush/blow out any dust and debris until the housing, sensor and impeller are clean. Reassemble the unit with a very tiny amount of grease on the spindle ends. Fitting as all Haynes manuals so eloquently say, is a reversal of the removal procedure. Hopefully now you should a peaceful drive without the persistant buzzing sound of the fan on the ICTS.
My thanks once again for the advice of the ever helpful members on the Discovery II forum.