Lexus ES 300 Forum : “Concerning a 1994 es lexus, have many owners had the problem with the instrument...”

This is a very common problem.  The needles tended to overheat over time and the SMDs lose contact and segments go out, or all together.  The Temp and Fuel are a little more robust.  If other lights are working (in other words not a fuse or the dimmer) then you are looking at a very expensive replacement cost.  Getting the parts from ebay or the junk yard mean that they could be just as worse off.  Mine failed at around 12 years and I replaced them.  I keep the brightness down to try and buy more years out of them.  I'm just noticing the fuel guage lose a segment when the car has been left out in the sun on a hot day.  When the A/C cools things off, it comes back on.

As for the A/C control backlighting.  These lights are soldered into the display, and a replacement display is the easy way to fix it.  You may have luck at a electronics repair shop to solder in new lights.  They are not replaceable.  Same with the Radio.  The lights for the HVAC buttons are replaceable, as is the backlighting of the guages.   I had at least 5 bulbs out after 12 years.