See if these help.

 

Try a wet vac first just in case it is plugged bad. Even a short burst of air can rupture a hose. Plus a vacuum will remove the dirt instead of blowing it up into the evap core.

 

XAOS777, thanks for the videos to help me locate the drain line ends.
nstoolman1, excellent suggestion, thanks!

 

Got the line cleared - Niagara Falls has stopped!

 

Probably a whole lot less stinky, too. Standing water in the evap tray is often likened to the smell of a pile of unwashed sweat socks in a gym locker.