I just purchased a 1998 Astro Van. Has AC and rear heat/AC. The heat and rear heat all work well EXCEPT that the front blower does not work on HI speed (LO and the two intermediate speeds all work as they should).

Based upon my limited research, I believe there is a HI speed fan relay somewhere on this vehicle (maybe the firewall). If this is correct, can someone point me to the location?

If not correct, does anyone have a suggestion as to what is wrong?

Thanks in advance.