A/C Smells

I had some mice get into my foam cut out air duct that runs from one end of the trailer ceiling to the other. Of course it was more of a mice smell verses mildew...

I finally had to drop down all of the ceiling registers and clean everything out of the ducts with vacuum hose...

Roy Ken

Used to get that smell in my old farm truck. Dirt would plug the condensate drain, moisture wouldn't evap and you'd get the mold smell. On really humid days, you'd get a flood of ice water spilling into the cab, too.

Lyle

You can buy a spray specifically for this purpose at a Ford dealership. You simply spray it into the grill intake until it's dripping out of the vents and then let it sit.
Ford uses it for warranty work and it really does work.

When I worked with Mercedes Benz we had issues with smells from the ac box. It had to do with growth of bacteria in the box, check that the condensate drains are working properly without restriction to start. They had a system of spraying a chemical into the heater box that killed the growth and that seemed to resolve the problem. On rare occasions we had to remove the box and replace the evaporator assy with one that didn't support the growth . Ozium spray works real well at killing odors and thats a simple fix. Lysol was something we used but it always seemed to return with time.

try changing the filter maybe there is some mildew build up in there.

Clean your coils, you have mildew growing in the evaporator coil. :)

Try spraying some Lysol into the intake of the AC and see if smell goes away.

Interesting you mentioned this. Immediately after having an AC unit installed in our bedroom, ours smelled the same way. I know for a fact we don't have leaks and mentioned it to the techs, but they couldn't find anything either. Only thing I can figure is that it has something to do with the foam core insulation. Don't know if your's would be related to the same. Seems everytime we turn it on, there's some bits of foam core that fly out.