Safety first: Disconnect power before accessing internal components.

Step 1 – Listen for fan operation: Start a short cooking cycle and listen for the cooling fan. If it is excessively loud, grinding, or silent, there may be a fan issue.
Step 2 – Check external vents: Ensure that the external exhaust or recirculation vents are not blocked by cabinets, filters, or grease buildup.
Step 3 – Internal inspection: With the cover removed and power disconnected, locate the cooling fan assembly. Check for foreign objects, grease buildup, or bent blades preventing rotation.
Step 4 – Test fan motor: Spin the fan by hand; it should move freely. Test the motor windings with a multimeter. Replace the fan motor if seized or electrically open.
Step 5 – Wiring and control: Confirm the fan connector is tight on the control board. If the motor is good but not receiving power, the control board fan driver may be defective and require board replacement.

Microwave shows E08 and the cooling fan runs at high speed or not at all during operation.

Possible Causes