Diagnosis
The primary safety interlock on the K400 prevents operation if the blending jar is not perfectly aligned and locked onto the base, or if the lid components are not fully secured. The illuminated power light confirms the base has electricity, but the motor circuit is being interrupted by one of these safety features.
How to Fix It
- Unplug the blender for safety, then remove and reinstall the jar. The jar's handle must face directly toward the control dial, and you must feel a distinct click as the jar settles onto the jar pad.
- Check both the main lid and the smaller center cap (the "Fill & More" cap). Press down firmly on each until they seat completely with no gaps.
- Plug the blender back into a wall outlet. Turn the variable speed dial from the "O" (off) position to a numbered speed setting. The start button should now activate the motor.
If That Didn't Work
If the blender still won't start, it may be in a thermal or automatic shut-off state. Unplug the unit and let it cool for at least 30 minutes if it was recently used heavily. Also, the K400 has a 3-minute maximum run time on variable speeds; if it stopped automatically, you must turn the dial to "O", wait a few seconds, then select a speed and press start again. Finally, inspect the jar pad on the base for any food debris that could be preventing the jar from seating fully.
Heads Up
Always plug your KitchenAid blender directly into a grounded wall outlet. Using a power strip or extension cord can cause insufficient voltage, leading to performance issues or internal damage.