It took a little searching of the web to find but it ended up being rewarding. The mini dash bulbs that many end up paying $6-$12 each for are available for 20¢ each here:
14V NEO-WEDGE BASE LAMP | AllElectronics.com

I bought 40 bulbs for $8 +another $7 for shipping ($15 total.) Ordered Thursday afternoon, received Saturday morning. The color of the filter doesn't matter much if all are replaced at the same time (silly not to at this price), only the most finicky would notice a difference. A bit brighter (again, probably the difference in the filter) but one could swap filters with their OE bulbs if so concerned. Or, one could pay eight times more (Gasp! $1.60 each) here for bulbs with blue filters:
Neo-Wedge
Or even just buy new filters for $0.49/each (although paying more than twice the cost of the bulb and socket just for a filter would be silly):
Autolumination Instrument Panel Light Bulbs & Lamps) (scroll to the bottom of the page)

I thought about just selling them here for $4 each. Hmmm... 40 bulbs cost $8, sell those for $4 x 40 = $160. Wish I could make that kind of ROI in the stock market!

 

My A/C temperature display light is out. Would these be the right bulb for this display?
I wouldn't want to have bulbs too much brighter or dimmer than the others.
Would you know the standard trade bulb number for the bulbs used in the A/C and Radio section of the (2006) XK8? That way people could look up wattage, brightness, and size information to pick alternatives.
Also, do LEDs work OK with the dimmer, i.e. do they get brighter and dimmer like regular bulbs?
Thanks,
John

 

Yes they will fit, I had to buy some from Jaguar at $5 a pop as I can only find LED style ones which are like laser beams and rubbish in the UK -_-

 

Thank you for this posting, just ordered some for my car!

 

If you find the bulbs you need are the even smaller ones these can be 'persuaded' into place.

 

Now you have me concerned or confused. I followed the links in the prior posts and got lost. There are dozens (hundreds) of different bulb possibilities with many different bases possible. So I fell back and ordered some of the $0.20 (20 cent) ones from AllElectronics.com. Great buy! Then I read some other posts. There are references to 194 bulbs (sounded like they may be too bright) at 25 lumens and 161 bulbs (12 lumens) might be good.
These neo-wedge bulbs from allelectronics are rated at 6 lumens.
Will these be too dim for the A/C Temp display?
Does someone have an original Jaguar bulb to look at (actually, I think there were 2 different bulbs, so perhaps these are right for the smaller ones)?
Does Jaguar bulb have any generic trade bulb numbers on it?
Or a working one that you could measure the resistance, please?
From that, I could probably figure out the specs on it.

And then the new comment "if you need the smaller ones you can force these" is not too reassuring either.
Please forgive me, but it is too much work to pull the A/C and Radio to replace bulbs only to find out they are too dim (or bright for that matter) after putting it all back together.
And LEDs are a crap shoot because it is very hard to figure out proper brightness and they tend to not spread the light but be very bright in a small area.
So are these a good recommendation or not?
If not, what is, please?
Thank you.
Confused in Austin.

 

Take the filters (condoms) from the original bulbs and install on the replacements, you'll have same to possibly a smidge more light than original. 194 bulbs are a lot larger and have no base. Typically used in turn signals, license plate lights, etc. on most cars. I don't recall any 194 bulbs in the center switch packs or hvac controls. The size difference is probably 1-2 mm, when I say 'persuade' I mean they can be pushed into place with a little extra grunt. This precludes having to purchase a few of the smaller neo bulbs - there are three sizes available but why buy when not absolutely necessary?

 

A not well known trick with the round, bullet nosed LEDs is to countersink the nose to have a 45 degree inverted cone shape (most drills have a 135 degree point which gives a 45 degree countersink) and then paint the nose cone with silver paint. This causes the light to get spread out rather than shining as a beam. If you still have some LEDs, try it and see if your LEDs could then be be used.

 

Over thanksgiving I replaced the bulbs in the A/C temperature display with the 20 cent ones, which are the neo-wedge bulbs from allelectronics and are rated at 6 lumens, drawing 0.1 amps (100 mA) at 14 volts . Bulb diameter is 4 MM by the way.
Sadly, these are not bright enough and do not compare with the ones in the Radio display, for example. So these would probably be OK for some locations but I need something about twice as bright. Have to do some looking around or on ebay for 4mm bulbs with a higher rating. I don't have the time or patience to experiment with LEDs (to take them in and out several times comparing results) and which are a crap shoot in terms of brightness in that you never know how bright the ones you get will turn out to be when all is said and done and you are not likely to find the same ones ever again. Incandescent bulbs are a lot more predictable in that regard.
Anyone reading this have a genuine Jaguar one out and could measure the resistance of the A/C temp display (back light) bulb? Both mine are dead. With that, I could find a perfect match.
Thanks.