windstar power window problem

Our 2001 Windstar has an intermittent problem with the driver side power windows (both front and rear). Sometimes (usually) they don't
work... you can push the buttons and hear a clicking in the "electronic module" under the dash, but no motor activation. Any ideas of problem cause and how to fix?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.