Hi, new member, just seeing if i could find some help on figuring out why my fuse keeps blowing for my ac. Its a 1990 4Runner, it blows while shifting, my AC switch light is not on, but when replacing the fuse, it works until i start driving it, then i shift from like 3rd to 4th and the ac dies down and the fuse blows then the fan kicks high again. anyone know why it may be doing this? where my short might be? the AC switch?

 

I suggest you check your schematic if that AC fuse also supplies back--up light switch, neutral safety switch and whatever switches AND wires go to your transmission. Then, inspect them all.
Toyota nomenclature is messed up. "AC Fuse" may not mean ONLY AC but "AC, etc."

 

So when the fuse blows the fan speeds up right?

If so, sounds like something in the ac circuit is sure drawing a lot of power.

Does the ac work ok initially when idling?

 

A problem well-stated is a problem almost solved...
AC dies down as in no more cold air- meaning compressor disengaged - but blower fan kicks high?
Which fan do you refer to? Radiator fan? Blower fan?

BTW... Wrong forum. You'll get better and ore accurate responses from people who own similar truck if you post in "classics" section.