Unit is a 4TEE3F6B1000B about 2 years old. Vertical install sitting on cold air return plywood collection box. Water is draining through drain pipe, however most is running down inside of unit and is running across garage floor. Drain line appears to be open, drain valve appears to be working fine as the unit will shut down when removed. Do not think there is a secondary catch pan as instructions suggets its removal for vertical installs. What is best method to troubleshoot and minimize costs? Thank you.