So this can be a problem area. In the D series they handled it both with a manual cable and with an electro-mechanical setup that had a controller in the dash. Sometimes the cable goes bad, even on the fancy rig. That happened to mine, and apparently the solution was to tape off the vent holes, whack off the cable, and remove the actuator which was above and behind the spare tire. The most sensible fix seems to be a new manual cable, which is reasonable for how heavy duty it is, but installing it, or more to the point getting the old one out is the challenge as the end of the sheath is in a pretty inaccessible spot.
Well I've done it, and once you know how it isn't quite as bad as it looks at first. To be sure, you have to pull the spare, the defroster/AC panel and lay on your back working overhead, but once you have the 90 degree flexible coupler (fresh air duct) removed the job becomes a lot clearer. There is a clamp with two 10-32 phillips head screws that holds the sheath, and the cable makes an immediate 90 degree bend. On mine the screws were rusty. I got the bottom one out but the head on the top one stripped, however I was able to spring the bracket enough to get the sheath to slip out.
Putting in the new cable should go smoothly enough. I'll position the handle right next to the other one that controls the heat. Getting the duct back in will be a pain of course but then I can button up the front area. In retrospect the fear and loathing of anticipation and the unknown were much worse than the actual job. Figuring out how to do it was the key, and now all y'all know that too.
Jim
