92-99 Burb Convert Rear Air to Rear Heat & Air???

Hi gang. Maybe someone can help me with my 93 K2500.
 I have rear AC, but not heat. Has anyone ever played around with converting a rear to Heat & AC when it only had AC??? I took some pics today at a junk yard of a 94 that has heat and air. Now I can open up the right rear of mine and see how it compares. I also have pics of the wiring harnesses under the headliner at the rear controls. I'm dreading pulling my headliner down to see if there are extra or unused harnesses there. Since the factory wires many harnesses with connectors that may or may not be used, there's a chance it can be wired by adding the correct parts. I just wonder if you guys (like me) that just can't leave well enough alone have tried doing this. I have access to any parts from a Heat/AC vehicle, but wiring might be the biggest problem.
 
Thanks, Dave 


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i would just run wires underneath vehicle following me heater hoses as u will have to run the heater lines underneath the vehicle just be careful removing from donor vehicle as to the best of my knowledge its aluminum tubing running underneath with rubber heater hose connections and the front is a y type hose

Good idea on the wiring. I'm looking on Ebay for a factory service manual for wiring diagrams among other things. I wasn't thinking enough and didn't look at the yard vehicles how the plumbing went under the vehicle. I'm guessing of the 6 trucks that are there at least one will be intact. Maybe I'll pull the headliner this weekend to get a look at the wiring on mine.
 
Dave.