Water leaking from bottom of furnace when air conditioner is running. Humidifier was on winter setting. Can a humidifier being on with the air running cause excess water in the system and leak on the floor?

First check the A/C drain for blockages.

Water is leaking at the bottom of furnace.The drain is not blocked. The A- coil/evaporator is not frozen. The pan under the evap. Does not seem to have any holes. I made a cut out on the plenum and could not see any water dripping while the a/c was on. It is a 2 year old high eff. Furnace but the a/c is over 13 yrs old. I am still getting cold air although it leaks.