If your HVAC blower runs only on "high" chances are you need to replace the blower motor resistor (about $15). The blower is designed to run through a series of resistors on low and medium. The "high" setting bypasses the resistor. If the resistor burns out, only high will work. The resistor can be found by placing your head or better yet, a mirror on the passenger side floor mat and looking up behind the glove box. Use an 8mm socket to remove the 2 sheet metal screws which secure it to the blower housing. Should be about a 10 minute job.
Below is a link to my Photo Gallery showing location of the resistor.

https://www.f150online.com/galleries...w.cfm?num=9470

Hope this helps. - Mark

 

This info was a great help..thanks...It took only 10 - 15 minutes. I bought my resistor at a Ford Dealership for about $30 Cdn. Fan is now working with all speeds available.

 

Mark - What if the blower motor does not run on any speed? Mine was working one day and then not at all on the next. I checked the fuse and it is OK. Does the fact that it does not run on High, indicate issues with either the switch or the blower motor itself. Do you know how to get the switch out.

Thanks, Wes

P.S. the photo on the blower motor are really helpful. Thanks for sharing that.

 

Mark hasn't visited this site in a year and a half.

You're responding to a four-year-old post...