Not sure if I'm correct in saying this, but here goes. Behind the accumulator for A/C is a black box on its side that I think houses the expansion valve and evaporator. Why, when the engine is running would this part of the system leak water profusley on the ground? Heat and cooling works fine. Jeff

I believe this is normal, sounds like it is leaking out condensation when using the a/c or using the defrost which both pull the humidity out of the air and then it leaks onto the ground.

Not sure if I'm correct in saying this, but here goes. Behind the accumulator for A/C is a black box on its side that I think houses the expansion valve and evaporator. Why, when the engine is running would this part of the system leak water profusley on the ground? Heat and cooling works fine. Jeff

As said it may be normal.
If everything is working good on the ac and heater system.
Check the AC operating pressure.
A freeze up in evaporator could do that to.
Or air pressure on the road blowing back pressure on drain.
A longer drain pipe would help there.
MT