Clearing engine codes

["C. Krafft" <ckrafft@olg.com>]

After reviewing info on 12V pages on dumping diagnostic trouble codes, I
have noted a few differences between the description and sequence of
display they describe and what occurs on my 93 100 CSQW.  When I short the
two pins, in this case the pair towards the front of the car, I get the
engine code.  I just discovered that I need to short it again to get the
next engine code, and so on until all the codes have appeared.
Question is, how do I then clear the codes?
At present, I'm getting a whole arsenal of codes
2342, 2312,2332,4422,2331,2341,and 1111
Car was in the shop last week and they claimed to have checked and cleared
the codes, but based on my latest test, I suspect they didn't. (More on
that later.)
Any help appreciated.
Also, getting an array of codes on my climate control system
11.5, 11.6, 13.7 (these have been there for a while)
and 17.0 and 29.4.
Any suggestion on how to clear these codes.
Thanks,
Charlie Krafft