My furnace appears to have started leaking today. I know nothing about furnaces. My AC is on as we are in the dead heat of August. There is a black *box* on the furnace with a small PVC pipe running into it. Not sure what this is but that is where the water is leaking from. What is this and does anyone know how to fix it?? Thanks in advance for any help!

Can you post a picture?

How big/small is this box? Does it have any other pipes to it? Does it say anything?
I'm wondering if it might be a humidifier... only thin I can think of that would have water to it on a furnace. Unless its just condensation coming from somewhere because of the a/c

Pictures please :)

That black box might be a condensate pump. If it is leaking it is not working correctly. It will be best for you to call for ON SITE SERVICE and get it fixed correctly before any damage happens.