Ok, so this is my first time posting here, namely because I have no clue what's going on. I'm fairly mechanically inclined, and I have had my truck for about two months now. My problem is pretty simple, yet endlessly annoying and entertaining, for you see every time I switch into four wheel drive, my air conditioner diverts air to the defroster. Now I normally wouldn't care about this and write it off as a quirk of the vehicle, but I live in the unpleasant part of Wyoming, where it is 80 degrees, and I have to climb fairly substantial hills, and my truck won't climb unless it is in four wheel drive..... so it gets hot and unpleasant. What do I do to fix this?

 

Correction, the 4wd system will not come on, I have to manually lock in the front difs

 

You have a vacuum leak.

First thing to check is the small diameter (hard plastic) gray vacuum line to the heater hose valve. See if it has been disconnected.

 

Alright, thanks

 

Edited the previous post to include a pic.

If it isn't this, post back up and we can go through the other possibilities (vacuum pump issue, leak at a 4WD hub, leaking solenoid valve, etc).

 

Ok, the line was attached, waiting for engine to cool so I can touch it without getting ten billion burns. As I said before, the 4WD system does not activate automatically, and refuses to engage unless I manually lock the hubs. That in combination with the defrost divergence, leads me to believe that it is in fact an electrical problem, and that two wires that have no business being crossed are crossed. Everything seems to work fine otherwise....

 

Do what you want, but your symptoms are exactly what a lack of vacuum will do (you are not plowing new ground here). Your blend door controls are vacuum and default to defrost. Your 4WD hubs are vacuum operated. Your heater block valve is vacuum operated. Your brakes are NOT vacuum assisted (another point some people try to make when they are informed of a vacuum issue). I would at least check out the vacuum pump and verify that you actually are getting vacuum .......

best of luck

 

Ok, it looks like a vacuum issue, and I am an idiot.... so what do I need to check

 

Not saying that at all. You asked for help on a problem that is common. Maybe it is electrical, that is not the common issue for your problem. You asked for help and then seemed to reject it. I have no problem with that if that was your intent (and it seemed to be to me - if I misread your intnet, then I do apologize for that).

If you are willing to invest a little time, then find the vacuum pump (passenger frame rail) and the solenoid and see if you are getting vacuum. Even more simple, pull the heater line off and stick your finger on it and see if you are getting a vacuum.

If the 4WD system works w/ the hubs in manual, then the transfer case (electrically operated) and the 4wD switch are working fine. The issue then would be with your hubs alone (nothing electrical to them).

 

If it does turn out to be a vacuum issue, I have a pretty thorough troubleshooting guide for that.