2002 windstar blower motor intermittent

when I start the van in the morning, the blower motor works fine and I can get hot air with it set on heat or cold air with the AC on, however, when I start the van in the afternoon when it's hot outside, I can't get ANY air out of the front vents. The rear climate system seems to work fine, but nothing comes out of the front vents. Any ideas?:crying:

Sorry for the delay.
The first thing that comes to mind is the blower motor speed dropping resistor.
This failed on my '96.
This part is located under the glove compartment.......
As you select different blower speeds, you select different resistor values in this unit.
I found the part on the Rockauto website, under "Heating and Air Conditioning", "blow motor resistor". Genuine Motorcraft brand is $16.59
NOTE.....make sure to get the FRONT one.......they list both front and rear (for auxillary rear unit, if you have that).
It is easy to replace (MUCH easier and cheaper than the blower motor unit).
Another possibility would be the actual blower speed switch....or even a wire that is disconnected.

Pictures of the blower speed resistor on my '96.

http://inlinethumb18.webshots.com/18513/2179949380011220610S500x500Q85.jpg (http://rides.webshots.com/photo/2179949380011220610gXNEtG)

http://inlinethumb23.webshots.com/50134/2867316990011220610S500x500Q85.jpg (http://rides.webshots.com/photo/2867316990011220610bNnXSG)