What's a good weight lifting schedule for the summer for a 17yr old that's going into the air force?

3-4 times per week. All the armed services require a high level of fitness in order to succeed. You are to be commended for trying to maximize your fitness prior to going on active duty. Vary the muscle groups you work throughout the week. Endurance and strength are both important to obtain. Weightlifting 3-4 times per week is fine. Talk to your recruiter for more specific recommendations.
Remember cardio. Don't forget to do the cardio. The weight lifting requirements for the air force aren't nearly as difficult to meet as the cardio requirements. You may want to consider a regimen of running/swimming/biking now.
USAF PT. Check out this article & the attached links to help prepare yourself for air force basic military training: http://www.Military.Com/military-fitness/air-force-fitness-requirements/air-force-basic-military-training-fitness-test.