What is causing a musty smell from an air conditioner?

Answer by  soundoff (121)

A combination of dust and moisture is what causes musty smells. Long story short, you're growing something in there and it isn't nice. Clean the a/c unit out. Especially the evaporator pan and it's drain if it has one. Dust is usually organic and moisture will make it mildew.

Answer by  Kurt (4579)

The musty smell might be coming from accumulated dirt in the air conditioner filter. You should clean out the filter for your AC unit regularly.

Answer by  wallaby78 (2293)

The musty smell from your air conditioner is most likely caused by mildew or mold. Try replacing the filters and wiping down all vents and interior surfaces with bleach or another strong cleaner.

Answer by  cb81 (613)

It is possible that the musty smell from an air conditioner is caused by the filter being not cleaned for a long time. You need to take the front off it, and clean the filter to remove the dust.

Answer by  mahavin (589)

whenever the Air conditioner gets heated or plugged by dust particle or more spores getting into the system it causes the musty smell

Answer by  kipcat (1964)

Normally moisture has been trapped in the unit or duct work and dust/dirt has gathered at that spot and began to deteriorate. Sometimes the evaporator pan will build a residue of sludge that can be neutralized by adding some bleach.