There is a service for this, the dealer or an independent mechanic can do this.

Cause is usually a blocked or partially blocked condensate drain under the car. If you get the system cleaned out and the drain cleared I would at that time also get the cabin filter changed out.

 

Is this service covered under warranty?

There is a service for this, the dealer or an independent mechanic can do this.

Cause is usually a blocked or partially blocked condensate drain under the car. If you get the system cleaned out and the drain cleared I would at that time also get the cabin filter changed out.

 

Agreed with Napster.

I encountered a few of these at the dealer (Toyota), the condensation drain tube can get clogged with leaves and debris and then water builds up which causes mold.

The fix was sticking an air hose attachment in the drain tube and blasting out the debris, whole bunch of water drained out. Then attach the spray can to a nozzle on one of the HVAC tubes and spray it throughout the system.

 

I used this product for my older car twice about 5-6 years apart. Works great. However, I don't know what electronics may or may not be exposed in the air duct. Apparently acuras ECUs get fried using it because the ECU is exposed in the duct.
https://www.detailedimage.com/Einszett-1Z-M46/Klima-Cleaner-AC-Odor-Remover-P476/250-ml-S1/

I would use this if I knew for sure that there are no electronics exposed in the air duct.

There's a long tube that comes with the can. Just rig the tube down the ducts and spray. Not only is the ac smell fresh but the air is arctic cold.

 

Yes, the sprays work. Doesn't have to be a special brand. Lysol, Seventh Generation Disinfectant, or Meguiar's Air-Refresher will all work. It is more where you spray. Definitely change the cabin filter and spray inside the compartment before installing the new filter. Then while running outside air circulation, spray liberally into the left and right air intakes of the cowl under the hood (honeycomb grid below windshield). It will suck it right in. Turn the blower to high. Do it for both AC and heat. Lastly, spray liberally into the interior air intake under the glove box running inside recirculation on high. Important: Open your windows while doing this and avoid directly inhaling the air from the vents.

If you want to use the commercial branded products for cleaning automotive AC, consider big cans of foaming cleaner are available from Home Depot or Lowe's for household AC units. Half the price of the car stuff, same ingredients. Personally, I did not like the list of chemicals, so went with the simpler products above.

 

With the winter behind me, the smell started when I used the AC for the first time this year.

Suspecting the condensate drain was plugged, as per the one reply here, I cranked up the AC with the ducts closed and it must have blown out the plugged shiz. It smells fine now.