Chevrolet Repair: 99 Suburban, correct test, rear quarter

Question
I have a 99 Suburban. I just recently starting having problems starting it in the morning. Took to a shop they tested for a draw on the battery and found none. Said everything was ok.After i jump start it in the morning i have no more problems the rest of the day. What could i ask them to look at.Thanks for you help.

Answer
If you say it cranks and starts when you jump start every morning then I assume your complaint is the vehicle will not crank or start after sitting overnight for an extended time...correct?
Test the battery with a digital tester.
Test the charging system.
If both of them are ok and it cranks over with a jump, the most likely reason is a parasitic drain on the system. If you have a meter there should be no more than a 50ma parasitic drain.
There have been some problem with the rear heater/ac relays sticking causing battery drain. Remove the right rear quarter trim and disconnect the 3 relays. If it never acts up again then the relays are most likely the culprit.

Hope this helps,
Robert