Air Conditioning Stuck on in the Iowa Winter!!

Back2Baja

Test Drive
Location
Ames, Iowa
Hey all, need your expert ideas/advice on a weird electrical (?) problem. The environmental control unit on the dash is dead, and is stuck on high fan-level air conditioning.

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.

This is totally uncool. Well actually it's totally cold. Which is bad. :weep:And none of it makes sense to me. If it were battery problems, I'd have evidence other places. 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???
 

metzican

Suspension Lift
Location
Lafaytte, la
This is so weird.

Here is my train of thoughts,

The gauge cluster is acting like what happens when I have to jump my vehicle, aka the voltage is to low. But when the vehicle starts and after a few seconds of the alternator running everything kicks on. It almost seems like the computer is not getting the proper voltage. But this comes from the same battery that can start it.

If you own a volts meter check what it is across the battery before you start it. And check right after you start it.

Are there any lights on the dash?

There are also a few fuses off of the battery pos wire check these to make sure nothing is popped.
 

metzican

Suspension Lift
Location
Lafaytte, la
What I think is happening with your heat vs AC is one of two options.

1: that the flapper thing that switches between outside air and inside air is kinda stuck between along with ac vs heat. So when your sitting it gets the hot air. But when you start moving you get the outside cold air forced in like if you turned everything off (when it was working)

2: When they checked your antifreeze they screwed up and checked when the vehicle was running and it added air to the system so you need to burp your heater core. To do this park on a fairly steep incline nose of the vehicle uphill and put it in neutral and rev it up and down a bunch and your antifeeze level should drop and feel hotter air coming out. Normally when you have an air bubble the air being blown by the fan will be room temp to warm but not hot.


But I almost want to put this all on the alternator. As in it is still charging but not a high enough voltage. maybe somewhere in the 11.8-12.2v range instead of 13.8v range.
 

Back2Baja

Test Drive
Location
Ames, Iowa
This is so weird.

Here is my train of thoughts,

The gauge cluster is acting like what happens when I have to jump my vehicle, aka the voltage is to low. But when the vehicle starts and after a few seconds of the alternator running everything kicks on. It almost seems like the computer is not getting the proper voltage. But this comes from the same battery that can start it.

If you own a volts meter check what it is across the battery before you start it. And check right after you start it.

Are there any lights on the dash?

There are also a few fuses off of the battery pos wire check these to make sure nothing is popped.

Isn't it weird? I don't own a voltage meter, but I'll get my hands on one in the morning and check that.

All the regular lights are on in the dash, but no warning lights.

I checked the fuses on the back of the positive battery cable first thing. Nada. They're all fine. No bueno. :-(
 

Back2Baja

Test Drive
Location
Ames, Iowa
What I think is happening with your heat vs AC is one of two options.

1: that the flapper thing that switches between outside air and inside air is kinda stuck between along with ac vs heat. So when your sitting it gets the hot air. But when you start moving you get the outside cold air forced in like if you turned everything off (when it was working)

2: When they checked your antifreeze they screwed up and checked when the vehicle was running and it added air to the system so you need to burp your heater core. To do this park on a fairly steep incline nose of the vehicle uphill and put it in neutral and rev it up and down a bunch and your antifeeze level should drop and feel hotter air coming out. Normally when you have an air bubble the air being blown by the fan will be room temp to warm but not hot.


But I almost want to put this all on the alternator. As in it is still charging but not a high enough voltage. maybe somewhere in the 11.8-12.2v range instead of 13.8v range.

Option one is interesting. But is there any way for me to troubleshoot and see what that is? This is when I need a warm garage, a bunch of tools and an extra truck so I can tear into this one! Your option 1 doesn't account for what appears to be a total lack of electricity to only the heater/AC and the trip meter though, does it?

Option two...hey that's something I can do without tools! I"ll give it a shot. But yeah, I know, it seems so electrical--or at least part of it. It's too many weird problems at once...because the alternator not charging things to a high enough voltage would make sense for the gauge jitter, but not for the AC issue, right? And if either of your options are the cause for the cold, then I still don't have an explanation for the lack of juice to any of the heater/AC buttons...

I appreciate the brainstorming...keep it coming!
 

Back2Baja

Test Drive
Location
Ames, Iowa
No engine codes? A.K.A. check engine light?

That many issues the computer should throw a code?

This thing throws a light at me at the slightest thing, but nope. Not one warning light. Actually that's a good point. I don't know the electrical on this rig good enough to know this, but I bet one of you do: where does the power for that main computer that throws the codes come from? Could that be disconnected/interrupted somehow? Or would that shut down a bunch of other things?

I'll check more of the fuses in the morning. My hands were so cold I was just dropping them earlier...
 

Muadeeb

Nissan al Gaib
Admin
Location
Dallas
The computer that throws the codes is the ECU. If that was hosed, I doubt the engine would even run. I'm leaning toward alternator issue as well right now.
 

metzican

Suspension Lift
Location
Lafaytte, la
Option one is interesting. But is there any way for me to troubleshoot and see what that is? This is when I need a warm garage, a bunch of tools and an extra truck so I can tear into this one! Your option 1 doesn't account for what appears to be a total lack of electricity to only the heater/AC and the trip meter though, does it?

Option two...hey that's something I can do without tools! I"ll give it a shot. But yeah, I know, it seems so electrical--or at least part of it. It's too many weird problems at once...because the alternator not charging things to a high enough voltage would make sense for the gauge jitter, but not for the AC issue, right? And if either of your options are the cause for the cold, then I still don't have an explanation for the lack of juice to any of the heater/AC buttons...

I appreciate the brainstorming...keep it coming!

I don't know the electrical system very well. But if option A is the fault of cold air then this could be due to electrical issues. as it is all controled by a computer and voltage matters now days.
 

metzican

Suspension Lift
Location
Lafaytte, la
The reason I think it deals with voltage is when they hook it up to there system. I'm guessing this is a simulated DC voltage and steady and strong. They say everything works. So the only difference would be you alternator and battery because these are the only two things that supplies power to your car when not on the mechanics "positive power unit". This is of course trusting your source which you say is good.
 

Back2Baja

Test Drive
Location
Ames, Iowa
The reason I think it deals with voltage is when they hook it up to there system. I'm guessing this is a simulated DC voltage and steady and strong. They say everything works. So the only difference would be you alternator and battery because these are the only two things that supplies power to your car when not on the mechanics "positive power unit". This is of course trusting your source which you say is good.

Yeah, the more y'all post the more It makes some sense about the alternator. And my gut says the guys at the shop screwed something up...it's just they never have before so I don't wanna jump immediately on that boat...
 

Cyclemut

Wheeling
Founding Member
Location
Morrison, CO
The a/c being stuck on is a default of the system. Similar to when, in the old days, if there was a vacuum leak in the old heater control system, it would default to defrost. Today, when the defrost is on, the a/c kicks on too.
The problem is in your IPDM. You can try disconnecting the negative side of the battery for 10 minutes, reconnect it, cycle the key from off to on several times, then start it and see if it rectifies itself.
Also, check for a loose connection at the positive terminal, while you have the negative terminal off. See if either of the fuses at the positive terminal are loose or have corrosion on them too.
Also, look and see how they cleaned the terminal or if they screwed something up when putting it back together.
If ALL of that is good, you've done all of it and it is still doing the same thing, then pull your IPDM and take it apart. Yes, you can take it apart and clean it. Dollars to donuts you'll find corrosion inside there too.
I've modified them to get independent fog light control, repaired fan control (on a 350Z race car that needed high speed fan whenever either speed was called for by the computer), among other stuff. I've found corrosion in just about every one.
So if you've a lot of corrosion at the battery, you've probably got corrosion in the IPDM too.
To take it apart isn't anything hard, take pics with your phone, don't hesitate to go deep into it.
To clean it, put the parts effected in a pan with hot, black, straight coffee. Don't dunk any relays or fuses, just the metal and plastic if the main unit.
After it's cleaned up, look it over real good. Anything that's separated you can jump with a thick wire soldered into place. Then you'll have to clearance the pieces above it to clear the wire.
Or, GI to a junk yard and get a used unit and either install that or use pieces from it to repair your unit (preferable), so you don't run into any CAN issues or recognition issues that can throw a code.
 
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