I use a small window unit air conditioner in my bedroom. During recent humid weather it developed a mouldy / mildew smell. I cleaned the filter & sprayed it with about 2 oz of CS. I then sprayed another 2 oz directly into the heat exchanger.
The smell was gone almost instantly, but the surprising thing was that it began to cool better. I had to lower the thermostat! After three days, I'm still using a lower thermostat setting and the air coming from it smells fresh & clean.
