This is the third time it’s happened: I own a 2012 Civic and when it is hot out and we are in stop and go traffic the car will be fine, but then all the warning lights/dings will go off, the speedometer stops working, and the AC won’t be cold. Also sometimes the car will turn off. Once you leave it off and sit on the side of the road for a while (30 min to an hour) it will start up fine and then as you drive it the lights will start to turn off. Eventually the AC will be cold again - any ideas what could be causing this? The dealer has no idea!
During that 30-60 minutes what happens if you try to start the car?
Carri, is the speedometer visible and just stops registering speed OR is the speedometer not displayed at all?
I have access to many Technical Service Bulletins on this vehicle and several recalls. With more information perhaps there’s something available for help.
CSA 
The speedometer is visible - just shows 0 and won’t register speed.
If you try to turn the car on it’s like the battery is dead, nothing happens car just “clicks”
First things, first…
How old is the car’s battery? Was it tested recently?
Do you know if the battery cable / battery connections were checked and cleaned recently or by the dealer when they couldn’t isolate the problem?
CSA 
Battery is only a year old - it has happened with the old battery and the new and yes all connections were checked. It seems to be either a sensor issue or electrical because it only happens when we are going between 0-20 mph for longer than 30 minutes when it is hot out.