Coolant and Oil Temps drop when using the windshield defroster/floor vents
I noticed recently that if I run the windshield defroster/floor vent, at medium or hot temperatures that the coolant and oil temp gauges will move from their standard 2/4 position to 1/4 position.
This only happens when the defroster is selected. If I turn on the heat full blast the temperature never drops.
What could be happening?