4x4 high won't work

[Bankspowered]

My husband is in Iraq and I drove to Florida to visit my family. Well, if any of you live in Florida you know there is a lot of sand. I was at my sisters and her back yard is sand where I park my husband's 99 F-250 crew cab 4x4. Well, I went to turn around to leave and got stuck. Now it is a 6 spd and has the Banks Stinger in it so I thought I could get out without four wheel drive...also BF Goodrich all terrains.... Well, I was wrong. Of course it has the auto 4x4 so I put it in four wheel high and the back wheels were just a spinning. I tried everything and four wheel high would not engage. I put it in four wheel low and it works?? Also, why does the air-conditioning shut off? Needs the extra umph? Well, I drove it to my folks house and my Dad tried it. Four wheel high didn't work for him either but four wheel low did? He said he didn't see any vacuum lines that came loose. We had our clutch and transmission worked on 2 years ago to replace that piece of crap Ford puts in with a heavier duty pressure plate/clutch. We rarely use the four wheel drive anymore and haven't used it since the tranny was worked on. Do you think something happened when it was taken apart? Any ideas would be great so when my family comes up to see us next week my Dad can get a hold of it. Thanks.

AF Spouse
All kinds of Banks parts
Airaid intake
1987 Mustang GT
2004 Nissan Maxima SE

[mschn99]

the pieces dont add up, at first it sounds like a vacume problem, since your AC function changes.....but the fact that they engauge in 4 low puzzles me....

the test you need to do is find out if it works properly with the hubs manually locked in....that will answer a lot of questions......