AWD not working?

[kirwin2]

I replaced a failed transfer case a couple years ago in my 94 Safari AWD with another used unit. All has worked well since (30K+ miles later). However, I've noticed lately that the van acts like it's only working as a 2wd ? If the rear wheels are on an icy patch, one wheel will spin, and the front doesnt seem to do any work at all, even if the front wheels are in a spot where some traction is available. I've not had a chance to get the van off the ground to check anything out, too *&^%! cold lately.
I've not heard any noises from the xfer case, and no fluid leaks. This year we've had more ice than previous winters, so I'm not sure if what I'm experiencing is 'normal' behavior or not. The van drives just fine, seems to crunch through snow without too many issues. Any ideas?

[8490astro1]

The van does have a front differntial, which could be worn out. Otherwise, the best check is to place the vehicle on four wheel and get it stuck in the snow! I've only been able to do this once with my 1990, and it was spinning all four wheels! Worse case scenario, the chain broke in the transfer case. Are your front brakes sticking?

A good way to test is to put the vehicle in park, and raise the left and right front wheel arms, and then try to hand turn the wheels. If the wheels are turned straight, they should have "slop" but should not turn. If the right one turns the left one, the differential is working. If you can turn the wheels, or turn one of them, look under the van to see if the front drive shaft is turning. If it is, then the rear is disengaged from the front, and the problem is in the transfer case. If the driveshaft does not turn with either wheel, you have a bad front differential.

If you put it up on blocks or on a lift, all four wheels should turn together!

[kirwin2]

I think I found the problem: now that it's warm out, I crawled under to find the driver's side ront axle was loose.
But, it's loose coming out of the front diff, not in the axle shaft itself. And it will move in and out of the case! I'm guessing the clip that holds the shaft inside the diff snapped or popped out. I need to see how much work is involved in getting it apart. If the only option is to pull the pumpkin, this van will become a parts vehicle for my NEXT Astro/Safari. With 230,000 miles on it, it's not worth putting lots of time or money into.