'98 5.0 Mountaineer issues, AWD etc

[mountainman421]

Own a '98 5.0 Mountaineer with 202,275 miles. I love it and it has worked well for the 2-3 years I've had it. Does have a few issues (mainly electrical oddities), but motor runs great. Moved to from Texas to Colorado last fall and some things have gone downhill and would like to fix some stuff before it craps out on me.

AWD) I'm pretty sure the AWD system worked fine in Texas.. felt like it kicked in and got me through some muddy fields a couple times. Here in CO though we have had a very cold snowy, icy winter and I have gotten stuck many times. Took me half an hour just to get out my parking spot at work with just a couple inches of snow and ice on top of the dirt. I am certain the AWD system is not working for some reason. What are some basic steps to figuring out why AWD will not kick in?

Heater) My AC compressor was disconnected since I bought it and I don't care about the lack of cold air... However the heater used to work just fine, but this winter when I really need it, it's been crap. It blows real hot sometimes, but some days it just blows cool/cold air. Some days I hear a persistent high pitched squeal (seemingly coming through all the interior vents) when my heater is turned on (whether it's blowing hot or cold), and some days the squeal is gone (whether it's blowing hot or cold). Some days it will blow cold for several miles then all the sudden the heat will come through like a furnace, only to go back cold eventually. I have considered:
-checking/cleaning heater core
-checking/replacing blower motor
-checking/replacing Air Temp Door Actuator through the glove box

Any hints on where I should start?

I do have an OBD tool and I get these codes, although I have a feeling they have nothing to do with the AWD problem or the heater problem:

p0340 (CMP sensor and/or circuit fault)
p0430 (catalyst efficiency monitor and/or exhaust system fault)
p1309 (CMP sensor output signal fault)



Any hints on where to begin looking to fix my AWD and heater problems would be greatly appreciated!!

TIA,
mountainman421

 

[RomeovilleIL]

I suspect you are missing the front drive shaft. My experience with AWD have never had an issue with snow even up to the hubs. Unlike the 4WD Auto the AWD is mechanical full time connection of the front and rear axles so there should be no feeling of "kicking in". It the AWD chain was broken in the case it would not drive period.

Heat -- it's been covered a bunch of times, including by me. Search will find it quickly. First step is always check that the radiator (not just the overflow) is full. Then heater hose temps. Then interior parts/system.

The other codes are unrelated but will have milage effect.