Ford Repair: Auto Climate Control?, electronic control system, control system that keeps track

Question
I have a 98 ford explorer w/ the standard climate control. I was wondering how difficult it would be to upgrade it to the auto climate control?

Answer
Hi,
This is extremely difficult. You have to replace the entire heat/cooling duct/venting system, replace the harness to the controls or rewire them and you'll need an internal temp sensor. If you did this yourself and were good with wiring, you'd spend close to $1500.00 in parts if you bought them new.  The differences are substancial. I looked in to this myself and decided it just wasn't worth it. If you can find a wrecked truck and you can get all the parts needed and the harness, then it would be worth it if you really wanted it. I just added autolamps to my 2005 explorer and that was a major job - involving reprogramming the security module - not worth it at all, but I wanted that feature enough to do it. It cost me about $500.00 by the time me and Ford was done doing it. Cars are much more complicated than you would expect. In 1995 and newer models (including yours), Ford redesigned the Explorer's electronics so that there is a main electronic control system that  keeps track of every function electrical. I don't know that it has any heat/AC control signals going to that module but I wouldn't doubt it after seeing how many other things go to it for reasons unknown to me.
I know this doesn't give you the answer you wanted, but you'd probably wish you hadn't tried this if you do it unless you are very knowlegable about your truck electronics and electrical systems. You may consider going to www.helminc.com and order the manuals for the truck and take a close look to see if this is worth the trouble. You'll need three manuals. The shop manual 2 volume set and the EVTM manual (electrical, vacuum and troubleshooting manual). These will run you about $140.00 and they are the same books used by Ford. These will give you a lot of insight about the wiring using for both types of heat/CC system.
If you do this, make sure you disconnect the battery negative cable and put a fuse in every wire you add that supplies power. Don't attach any wires within 1 foot of the engine control module. That can affect the module performance.

If I talked you out of this - I did a good thing. I would say "go for it" for almost anything else except this one project.