2000 Chevy z71 extra cab. Question: coolant leak when I turn on the fan with the AC on or off? leaks at firewall low area , when i shut off the fan it stops.

Answer: It might not be a coolant leak. There is a drain on the firewall where the condensation from running the air conditioning runs out. This would like a puddle underneath the vehicle.

If you're sure it's coolant, you could possibly have a leaking heater core. Usually though, a coolant leak is present all the time if you have a leak, and not just when you're running the fan or air conditioning. The intake manifold could be leaking at the rear of the engine, that is a common spot for your Chevrolet Truck. Take a closer look at the ground when you see a puddle. If it's just water, there is nothing to worry about. If it is coolant, start checking for leaks.