Question, what size bulbs are in the heater panel, and how do you access them?
The bulb is a capless 286 size.
It’s pretty easy to get to the bulbs: First you take off the console as if to change the radio. Then the vent (or vent/AC) knob just pulls off and the 3 slider knobs are held on with small philips head screws from underneath.
Once those are off, the front panel is held on with press tabs - 3 top and bottom. Push them in gently and it’ll spring off. That gets you to the front of the bulbs. The right hand one is easy to pull out, but the left one is partly obstructed by the plastic light guide around the vent knob.
I noticed that the bulbs are housed in bayonet-fit lampholders, so I suppose it’s intended that they be removed from the back.
To convert to Led bulbs
These are the ones you need
http://www.aceparts.com/all-led-bulbs/dashboard-leds/t5-286-push-fit-dash-board-led-hi-brightness-1.htm
I got white leds off ebay with resistors for the rest of the switchgear , the heater controls ashtray dials are all done by a bulb kit you can get from ace parts
http://www.aceparts.com/all-led-bulbs/dashboard-leds/mazda-mx-5-eunos-led-dash-kit.htm