let's start from the beginning, i have a 1999 GMC JIMMY 4 door 4x4 4 button SLE the wire harness that goes under the driver floor board burnt and i had a non electrical shop re-wire it and they did not do a good job but, in their defense this is the first time i have seen wiring that has multiple wires of the same color and NO different markings or numbers on them !!! SO THATS THE BACK STORY NOW ON TO THE ISSUES.
the manual control **** don't switch from cold to hot, the heat is always on for the floor and defrost but, when i switch to vent, as it is changing it blows nice and hot but, when it settles fully on vent it only blows cool NOT hot !!! then, the rear defrost button stopped working at the same time. i'm not sure if it happened all at once but, i have checked all fuses and replaced all vac hoses looking at other posts that are close to my problems. i have had the glove box out and watched that actuator move, and on the drivers side both of those actuators move as well but nothing happens when i turn the heat cool ****. so, i don't know if this is an electrical issue, i'm sure it could be. if anyone would know how to troubleshoot / pin out the harness i'd really appreciate it.