Need help diagnosing my 2002 dodge caravan

Help with diagnosing your vehicle's concerns should be done at a shop near you by a qualified technician, not on the Internet hoping one of us will be able to tell you what's wrong with your vehicle based off of a vague description of the problem. Sounds like maybe your air conditioning compressor could be binding, causing extra strain on the engine when it is engaged -- which is when your climate control system is on in most any position. You'll need help to diagnose and repair this concern. Here's a link to find some folks near you: www.repairpal.com/repair-shops