Will that white cover come off? If it does you should find black twist off bulb holders that use the standard capless wedge 286 dashbord bulbs. I'm guessing this as heater controls use these bulbs which I have to replace on mine.
the withe cover can get off. but i think it would be difficult. because the 4 white circles seems to be connected to the indicators inside the housing. so if i take theese off i am worried that i break them.
there is only one wire harness going in to the housing on the back and it seemes ok