Also from answers.com :) –
If the pork chops are about 1/2″ thick, they will take a good 4 hours on the high setting or if you would like to do it all day while you are at work, you can put it on the low setting for about 8 hours. It will vary a little depending on the crock pot itself. A little longer will never hurt, you just dont want to keep them in there for hours too long.
Source:http://www.answers.com/Q/How_long_does_it_take_to_cook_pork_chops_in_a_crock_pot