I'm chasing gremlins on my tuck, two issues. First the HVAC system will only blow with the fan on high, and it only blows out of the defrost vents with the position selector switch in any position. Second is my reverse lights and turn signals quit togther at the same time... All fuses are fine, multi function switch is only a year old. The HVAC system is under warranty on a previous repair fom Ford, but any dealership in my area is backed up for a month on deisel repairs and I cant have my truck down for that long, any ideas?