i've never done it, and would remove the filter first, but i've also seen people use their steamer to blast through the hvac system. check out youtube.
Sure, that's the first place to look with a newer 2-8 year old car, check the cabin filter. And yeah, don't count on the dealer telling you they changed it, and of course charged you up the kazoo for it also. even so called good dealers do and will pull stunts. Don't blame the dealer itself sometimes, it's the lazy goof in the back who you unluckily got to work on your ride.
I've a friend, who owns a 2008 Chevy Impala, What a junk of a car, Chevy should be ashamed of what they manufactured-sold when they made such a car. Just junk! Go ahead, tear your brains out looking for a evaporator drain. I looked 4 times, 3, when the vehicle was on the ground, spending about 45 minutes total, and once while it was up on a lift, and searched for 20 minutes.....nothing.
Interior was flooding out, soaked, enough water to take care of a 1/2 dozen tomato plants. Eventually found it wasn't that, but clogged Sun Roof Drains, and there's 4 of them, two fore, and two aft. I got to the two front, seemed to fix the problem. What a nightmare ripping out interior trim panels,
And the Vent Blender Motors playing Jimi Hendrix "Machine Gun" every 3 weeks going bad, replaced a 1/2 dozen of those, being a contortionist, and no luck with those either, just a crap defective piece of junk chevy made with Chinese garbage on board.