Overheating Durango

I have a '01 Durango that overheats occasionally when the AC is on, usually when I’m idling in the school traffic circle waiting to pick up my kids. Turning the AC off helps it slowly get back to normal until I can get back on the highway again, and then it’s OK. Any thoughts? My dealer claims he can’t help me unless it’s overheating when I’m there.

Whenever the A/C is operating, there’s an electric cooling fan that’s supposed to run and pull air through the condenser and radiator. My guess is that this fan isn’t turning on. If you don’t hear a fan come on when you turn on the A/C, that’s the problem. There’s a relay that controls this fan that could be bad, or maybe even the fan motor itself is out.