94 850 NA Ac weirdness and window problems

[pmonk]

*update - more problems*

It works for a while (~15 minutes) then stops. If I turn it off, after several minutes I can turn the Ac back on and it will work again for a few minutes.

My question - could it be water freezing in the system and then melting, or the expansion valve. I have read of this in other vehicles. Is the expansion valve buried up next to the hard to get at evaporator.

Thanks,

-p