Fluid Sump And Case Components
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.
The thermostatic fluid control valve stores fluid in the area of the main control when the fluid expands due to temperature. When the fluid is cold, the valve allows more fluid from the main control area to return to the sump.
The transmission fluid level check is correctly carried out when fluid temperature is hot.