Should the temperature control switch in my '89 300CE actually be illuminated? I only recently noticed that the temperature control is dark during night driving and with headlights on!

I understand that the climate control can be tempramental, so should I just leave it as it or can the light bulb be replaced? If yes, anyone who has done this job before and can give me some pointers?

Also need to change my wiper blades. I am reluctant to just go to the local dealer who will most likely will charge me a mint.
Any aftermarket brand that is recommended, or should I stick to OEM?

Thanks

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1989 300CE (aka Schatzi)
2002 Ford Explorer