I feel your pain, as I'm an auto technician as well.
Had one saturday... ended up having to drive it for almost an hour to get the readiness monitors set (fixed an emissions problem and it will not pass the test with two unset monitors).
Also can't run A/C while setting monitors... also A/C didn't work anyway.
Never could get those suckers to set though. Did some research and found out the engine has to be started below 75 degrees... grr... THAT ISN'T GOING TO HAPPEN THIS WEEK! haha
The worst is first couple hours at work though... the sun beats down right into my bay. Must get 150+ with the sun beaming right onto your work area... but at least the guys on the other side of the shop have to deal with the sun in the afternoon... when it's hotter.. haha