When my over-the-range microwave's vent fan is on, it blows hot air from the vents above it into the kitchen. Is it supposed to do that rather than out of the house?
Do Over the Range Microwaves Have to be Vented Outside? – Pro Line Appliance
How To Install A Vented Microwave Oven - Concord Carpenter
Do You Need to Vent a Microwave?| Don's Appliances | Pittsburgh, PA