? Add on A/c for 1988

[Danny1988]

Hello folks,
Been a day or three since I've been here but like everyone, have trouble come running. LOL

Anyway was having trouble with the heater motor got into it and discovered this truck was a non a/c truck and has a add on a/c unit with it's own blower motor. both motors are controlled through the one blower switch.

my problem is, this http://www.bought4less.com/bought4le...3d2067b-p.html , is the only add on a/c kit I can find for a 1988.

I was hopping to find a wiring diagram to figure out how the a/c switch was switching between the blower motors they both seam to be working through the low and high speed relays on the fire wall.

If someone could point me in some direction I'd sure appreciate it.

Thanks, Danny