Microwave vent blocked by cabinet

I came across a microwave that the upper cabinet blocks the exhaust vent. This is a recirculator and you can see grease accumulating at the crack between the cabinet and microwave. Normal installation would have the microwave sticking out an inch to two inches to allow the vent to exhaust back into the room. Is this a defect or preference? Will it affect the performance?

Yeah, and it’s a fire hazard!

Did you read the manufacturer installation manual? I fully suspect they will tell you what is already obvious, and you pointed out, that it is incorrect.

Yes, yes and it’s a fire hazard, too.

It’s probably when the microwave was installed the motor did not get flipped. The motors are normally set from the factory to blow out the top. When they’re installed you have to flip the motor to recirculate.

Yes Chris. When you install a microwave with an exhaust fan there is usually a screw or two on the top of the oven that allows you to rotate the fan blower motor to blow forward (recirculate) or blow upward (blow through an exterior exhaust vent). So the fan was not installed properly.