Flakey AC problems

[Stage_wizards]

My 1984 300TD has some really flakey climate control problems. Only the defrost button works on the climate conttrol unit in the dash. Others won't come on until it has been pushed in. Sometimes. Other times they work as they should.
Had the A/c system recharged. Won't work properly when automatic switch is selected. Have to shut down the whole system and turn off the ignition to get the a/c to work properly. A/c cuts off at times, then comes back inexplicably, even in manual mode.
Now a/c doesn't work and auxiliary fan won't come on. Blows hot air from vents. I have a spare CCU. Will that fix the problem?
I have replaced fuse#14 and fuse #8. Sometimes I get another quirky problem when fooling with the a/c - the transmission won't shift out of first. Then it comes back fine. Sounds like vacuum problems.
Anybody solve these frustrating difficulties? Temperature outside was 98 degrees today.