Like Matt said.

Take a little square of LIGHT tissue paper and place it on the air intake grill near the dome light. If it will not stay, your sampling fan has failed.

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2012 E350
2006 Callaway SC560

Good idea - even though the sensor readings from the controller indicate "colder than should be" - if the fan isn't pulling air across the sensor, things won't work as designed.

I'll check it.