Customer stated there was water around the furnace and it was leaking into the garage. The furnace sits right above the garage so I started taking apart doors and watching for any possible water leaks. I then turned the humidifier on and let it run for a couple minutes and then water started overflowing and spilling into the ductwork. I found that the humidifier drain line was completely plugged up and therefore not allowing the system to drain properly. I removed and replaced the drain line with new tubing, once the new drain was on I ran the humidifier and found that everything was up and working properly.