1986 Cadillac Deville: 2 questions

In a strange series of events, I have recently been given a 1986 Cadillac Deville. There are only three things wrong with it: Paint job (80's paint death), Air conditioning (needs serviced), and the Tranny.

So, After reading the manual, the Chilton, and the net. I still need a little help.

One. Can anyone explain to me how to access the error codes using the data panel in the dash? I read somewhere you hold down the OFF and HI button on the heat, but it didn't explain things clearly after that on how to get to the bloody codes.

two. The original owner told me that it has a problem with the Tranny. Essentially whats going on is a shifter problem at around 35-40 mph and it only seems to really happen once or when its still somewhat cold.

when you press on the gas, the engine revs but it stays at the lower gear.

When it does shift if it was at the high rev, its like it is whipping over into the next gear.
(like holding a branch and suddenly letting go to hit something.) if you aren't careful, it makes a good thunk sound.

OR if you had babied it, it will after a little bit, it will shift almost normally.

Can anyone help me with these two problems?  

!st issue. The 80's Cadillac's CANNOT be converted to R-134 freon because the low pressure sensor is NOT calibrated for this type of freon and there is NO fix as of this date. You MUST convert it back to R-12.

2nd issue: to get the codes from the 4100 engine via the climate control panel and to CLEAR (erase) them is the FIRST thing you need to do to see if any codes return is done via:

1. Ignition switch ON, Engine NOT running.

2. Simultaneously push and hold the OFF and WARMER buttons for 3
seconds and release them.

3. Codes will appear as either E or EE followed by numbers such as E
15 which would be a HISTORY code or if it displayed as EE15 this
would be a CURRENT code.

4. After the E or EE codes all displayed the F or FF codes would
appear and the screen will stop at .7.0

5. To CLEAR the E or EE codes, Simultaneously push and hold the OFF
and HI buttons until you see E.0.0 and release the buttons.

6. To CLEAR the F or FF codes, Simultaneously push and hold the OFF
and LO buttons until you see F.0.0 and release the buttons.

7. Push and release the AUTO buttons and turn OFF the ignition.

8. Wait 30 seconds and re-enter diagnostics by repeating steps 1 and
2 as stated above and see what codes appear.

Let me know what codes appear.

Disconnecting the battery will NOT CLEAR the codes but will only ADD 2 codes that mean that you removed battery power from both computers.