1996 Chevrolet Lumina cabin water leak

1996 Chevrolet Lumina Van. Water began to appear in the interior driver and passenger compartment. My mechanic replaced the drain hose and the problem got worse. We now have at least a pint to a quart of water in the passenger compartment whenever we run the a/c or heater. The next step is to pull the dash, an $1100 expense, to see what is the problem. Do you have any other suggestions prior to this step?