Sour smell coming out of the windshield defroster

When I turn on my the windshield defroster a sour smell comes out.
I am trying to find out if there is a way for me, or preferably a car shop can clean the Inside of my front windshield defroster.

The smell does not occur when I use my regular A/C heating vents that face me when I drive. The smell only occurs when I turn on the front windshield defroster - that big long air vent closest to the front windshield.
I am worried that some liquid got into that area & is making it smell.

I don't know a lot about cars but I am not talking about replacing an air filter. **If so, my guess is that would be a secondary step, meaning the Inside of my front windshield defroster still needs to be cleaned if that's possible.

Other background information: I got it when it had 3,650 miles a maybe fourteen months ago (this car is not at 10,000 miles. I am only repeating it because when I first had my state inspection they do not believe the mileage at first and even the auto repair shops if I go to get a plug on one of my tires). The car was fixed up by a mechanic and had no smell/ventilation issues of smells coming out of any vents at all for an 13-14 months. Only in the past 30-35 days or so had the smell started.

Finally ill get to the last of relevant details, a friend was in my car and needed to urinate but I was not able to pull over for her. She peed into a container with with lid (plastic food container) I had and then placed the container later on my dashboard later on after I finally got to park (we were still trying by find the right location to dump it as we were out in public and I had eventually parked at a busy rest stop during the day. When she was ready to pick it up, we noticed a little liquid trail toward my windshield defroster. A little bit, or not a lot for us to have noticed that her pee was leaking out earlier. Honestly I didn't think much of it at the moment because it was a small trail of liquid - she wiped up what she noticed.

So basically my concern is the urine is causing that sour smell. It kicks and is noticeable in when I turn on the defroster for the first five to six minutes but at some point, maybe seven to nine minutes I don't smell it as strong. So far it seems to kick in for the First time I turn on the defroster that's when it's most sour/noticeable. So if I turn on the defroster the first time that day it kicks in- but the second time if I turn on the defroster again say fifteen minutes after having shut it off then the sour smell way is less potent it could still smell, it's just more subtle I guess it's like a very 'faint' acid smell in the air which I think I notice but it's not as anywhere nearly as noticeable as the first time I turn on the front windshield defroster for the day.

Finally my guess is you still may advise me to get the air filter replaced which I can understand I'm just trying to figure out if there's a way to clean the inside of the windshield defroster as well. I could try to clean it or preferably have a shop that agrees to clean it for me.



Thank you in advance for any advice you may provide.