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Does anyone have any experience of removing/cleaning this little fellow? I understand it's based on a hot wire principle with a little fan drawing air through a grille on the dashboard. My heater will push out loads of heat - even on idling speed - if I wang the control up to max. Similarly, the aircon will deliver arctic air if I wind it down low. So I know that the system is all working correctly except for, perhaps, the sensor. I'm guessing some partial dismantling of the dash panel is required to get to this part?

After a few years, these units get full of gunge but they usually respond to a touch of gentle cleaning. Just be careful not to be ham-fisted with it. Mike.

Does anyone have any experience of removing/cleaning this little fellow? I understand it's based on a hot wire principle with a little fan drawing air through a grille on the dashboard.......

If it's the same as the XJ8 (X308) it's not a hot wire but a thermistor bead. On the XJ8 I found that I had to remove the instrument binnacle to get my hand down the back to release the clips for the slotted grille unit. Anybody else got an easier way? Once you get that unit out the thermistor is fairly easy to clean with some IPA or meths. The fan is more difficult to get at, but a small paint brush does the trick. Beware trying to clean it with the hoover as the blast of air over the blades can over-speed the bearings and damage them.

Thanks Mike, Brian! Little job for when I get home this evening then! On the XK8, it looks like two screws at the bottom and the panel unclips at the top, revealing the sensor attached to the back of the panel. They call this panel a knee bolster!

Got the little chap out - not too difficult either. It was rather fluffed up as you can see. A gentle clean with a small paint brush was all that was required to transform the gunged up thermistor on the left to the gleaming bead on the right. While everything was out, I took the opportunity to plug the whole aspirator assembly in to check that the fan did indeed spin - it did. The thermistor measures about 1.4 kOhms at room temp and reduces as I warm it with my finger, so I guess that is ok too. I'll check it all out on the next trip.

Well done Mike! It looks a lot easier to get at than the XJ was. Let's hope that fixes the problem.