Everything should illuminate pretty evenly.

If the entire climate control panel is dimmer than say, the gauge cluster, then it's probably fine.

If a portion of the panel looks a bit inconsistently lighted, then it probably is.

Amazing what difference a single burnt-out bulb can do...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car