Hi.

The followed is the test procedure for the hood motor:

Unplug microwave oven or disconnect power. Remove wire leads.
Use a multimeter to measure resistance:
■ High Speed—Normal: Red (R) and Blue (BU) wires: 100 to 200 ohms
(approximate); Blue (BU) and Black (BK) wires: 40 to 100 ohms
(approximate); Abnormal: Infinite
■ Low Speed—Normal: Red (R) and Blue (BU) wires: 100 to 200 ohms
(approximate); Blue (BU) and White (W) wires: 80 to 150 ohms
(approximate); Abnormal: Infinite

Make sure there is nothing jamming the blower wheel.

Here are the breakdown diagrams and parts list for your microwave:

Model WMH2175XVQ2

Your motor Part number: AP5656382