Ford (06 Freestar) wiper question.

[Huskinhano]

We recently purchased a used 06 Freestar in very nice shape with a clean Carfax. Every single oil change and so on was documented. One thing I didn't check was the windshield wipers. They sort of work. There really isn't any effect on intermittent time when you try to adjust and only high speed works. On low speed, there is just intermittent....and long at that. I'm ASSuming there is some sort of module for this. Where might I start to look...besides under the dash : TIA