Cadillac: 4th gear problems, split seals, ac ducts

Question
Hi,
I have a 1991 Cadillac Deville 4.9L that at highway speeds doesn't go into 4th gear or at highway speeds the engine is reving real high. Also, the automatic climate controls not working, I can't get cold or hot air to blow out.  I would appreciate any guidence on these matters.
I have no actual mechanical skill, but follow directions well. Plus, a neighbor of mine has lots of tools.  

Answer
The most likely cause is burned 4th gear clutch plates due to worn or split seals on the piston.

Of which will require disassembly of the trans.


On the AC the most probable cause is a faulty blower motor and or a fault in the damper door in the AC ducts.