Musty Odor From Air Conditioner

You need to get up on the roof and clean the EVAPORATOR.

Get an evaporator cleaner at any box store.

You will be shocked at what you get off the evaporator coils.

Clean the evaporator coils, no more smell, cooler air and way better efficiency.

After you clean the coils, we read on this forum that if you leave the fan on "low" instead of "auto" when the AC is on, it will help dry it out so it prevents the odor. We do that and no more problem and we are from hot humid Florida!
Note: if you have 2 or more AC zones with one thermostat, the fan mode must be the same on both zones.

Turn on AC fan. Spray Lysol spray into the air inlet on the ceiling. It might take a bit.

After the Lysol gets in there the smell is gone.

Also works on car AC as well.

I guess that I'll be on the roof tomorrow...
Thanks for the rapid responses.

As always, the forum members come thru when
help is needed!

:h isn't that thing up on the roof called the condenser.

I always thought the evaporator was what is the cool part. On my fifth wheel that puppy is accessed from the inside by removing the ceiling panel.

Both evaporator and condenser are serviced from the roof. And, both should be cleaned while up there. Also look at capacitors and make sure they have not leaked or are swollen.

And with the poor quality of RV air filters, Lysol or other sprays can not remove all the crud where the mold grows. It would be a temporary fix unless the A/C is close to new (with little crud deposited on the evaporator fins).

Mildew, clean the coils. :)

Get a can of Ultrashield or similar auto AC deodorizer/fungicide from an auto supply store and follow the instructions. This is what every dealership uses to refurb its AC systems (to remove the smell, recharging is a separate topic) on trades, surely other folks on this forum have worked in a dealership before! DO NOT use Lysol as it can damage the actuator mode in the system. It might, it might not, but unless your system is under warranty you might want to avoid it.

Good info on not using Lysol, so I guess I'll stop! For what it is worth, I have one thermostat and 2 A/C's, 1 heat pump and the propane furnace. I can control them in just about anyway I want: furnace on, A/C on at same time. Or, fans any combination, or heat pump and furnace on, fans any combination.