Here's the particulars:
2011 Xterra, Pro4X
76,000 miles, no problems--ever
Took my car into a trusted shop I use, today. Had snow tires put on, oil changed and antifreeze checked (no space to do those things myself, uhgg!). My battery was corroded (badly) so the guys took it out, cleaned it up and put it back in.
When I started up my Xterra to leave, the following things happened:
--With the key just turned to the "on" position (where the dash lights come on and the gauges usually start moving), the in-dash lights come on but the gauges don't move.
--When the key is advanced on click further, the engine starts up, no trouble, but the gauges stay at their resting position, and vibrate back and forth about 1/8th of an inch. After a couple seconds they suddenly come to life and then function normally
--A few seconds after the engine starts running, the heater fan come on high. there are no lights visible on the environmental control panel, turning the fan or heat knob changes nothing. Pushing a button to choose defrost or heat, etc usually makes that button light up orange, but the whole panel is dead.
--While sitting in the parking lot the air coming from the heater into the cab is hot, but as soon as I started driving, it got cold. And not cold like cold outside (it's 31 degrees outside), but like aircon cold. The air has a quality like it's internally recycled air--like when the aircon is engaged.
--The in-dash light that shows when the traction control is disengaged was lit and didn't respond when I pushed the button to turn it back on. After driving for about 3 minutes, the light went off. (I couldn't tell if the traction control was actually disengaged because I was in traffic and couldn't check it out, but I doubt it. Nothing about the driving of the car has changed.
--Further investigation shows that when the car ignition is turned off, the trip meter resets itself to zero--though the clock doesn't and neither does the regular odometer.
Before driving away I took it back into the guys in the shop and they messed with it for over an hour, and couldn't come up with anything. They said that when they disconnect my battery and connect the Xterra to their positive power unit (?), their is light to heater controls and they work, but when they unplug it and reconnect it to my battery, the heater goes back to being dead--except for being stuck on full blast aircon.
The guys said they checked 52 fuse boxes (I didn't think their were that many...), re-cleaned the battery terminals and made sure there was a secure connection. Checked the battery and it's good. They said something about "relearning the computer" while they had it hooked up to their power source. At any rate, their electrical guy had no idea. (The guy who was relaying the info to me from the tech definitely didn't know his tech terms--he was a new office guy I think, but I've been taking the car here for oil changes for a year and they've always been great.) Called the Nissan dealer and the technician couldn't think of anything either and of course they're booked up until after Christmas.
This is totally uncool. Well actually it's totally cold. Which is bad.
And none of it makes sense to me. If it were battery problems, I'd have evidence other places. And why no computer codes/warning lights? If the environmental unit was as dead as it looks, then there would be no air, and definitely no aircon. Could there be some system design so that when the heater core goes out the electrical goes out on the display? That still doesn't explain the aircon though. Ideas???