Prevent Mold Growth in Airconditioners | Allergy

Prevent Mold Growth in Air Conditioners

by Allergy Guy

Air conditioners will grow less mold if operated in a specific way.  In this article I will explain why this is and how to operate them correctly to reduce mold growth.
Air conditioners are notorious mold producers.  In this article I will explain why this is and how to reduce this problem.

Air Conditioners Grow Mold – the Reason

Here is what mold requires to grow well:

  1. Moisture
  2. Food

Those are pretty low requirements.  Mold grows so much better if it is dark, warm, and the air doesn’t move.

Now let’s look at the inside of an air conditioner.

It is moist, because cool temperatures cause moisture in the air to condense.  Removing moisture from the air is almost as important to comfort as reducing temperature.

It has food, because the air conditioner is constantly taking in dust-laden air from the room.  This sticks to the wet cooling fins, where it sticks.  Central air conditioners don’t have this problem as long as the air filter is properly installed.

Temperatures are cooler than ideal for mold, but not cold enough to destroy the mold.  When the air conditioner turns off, the temperature rises and becomes perfect.

It is pretty dark inside an air conditioner.

When the air conditioner is off, the air does not move.

Preventing Mold Growth in Air Conditioners

A dry air conditioner will not grow any mold.  This is the key to cracking the problem.

The solution is simple: run the air conditioner on fan only (cool off) for sufficiently long to dry out the interior.  I have seen it suggested that the air conditioner should run for 2 hours.  Even 15 – 20 minutes should help substantially.  This will work for split air conditioners, window-mounted (“window shaker”) models, and car air conditioners.  In the case of a car air conditioner, even turning off the air conditioner and running the fan on high while recirculating the air (which will be much dryer than taking outside air) for a couple of minutes makes a huge difference in my experience.

For central air, this should be unnecessary, as long as the dust filter is properly fitted.

Have you tried this method?  How does it work for you?  Leave a comment and share your experiences.

This comment from John might be interesting to some:

These modern air conditioners sling the condensate on the condenser. The dust,and anything else in the air plugs the condenser. The dust along with the wet conditions cause mold to grow. Solution, forget the warranty, my health is more important.I am going to drill a drain hole in mine

(Visited 4,918 times, 1 visits today)

Leave a Comment

{ 6 comments… read them below or add one }

1 sandy August 29, 2016 at 17:35

can i spray bleach water into air cond, front and backi. i am not able to take out and clean as i am too old. thanks

Reply

2 Eric Taylor December 12, 2016 at 08:58

Diluted household bleach put into one of those hand pumped sprayers works very well. It kills the mould for about 3 months. Only snag is that if the fins are very close together, in time, the bleach which is sticky tends to clog the airflow through the fins. You then need to try and remove the residue with steam or maybe a hot water spray.
You can also use ordinary mould remover bought at your local supermarket. It behaves in the same way as bleach

Reply

3 Allergy Guy December 14, 2016 at 20:22

I would suggest that the stickiness is not in the bleach, but in the goo formed when bleach attacks mold. Also, bleach kills mold on contact but has no lasting effect. So best that you spray your air conditioner weekly or even more often, and then you should reduce or eliminate clogging problems. That’s my theory.

Reply

4 John April 24, 2015 at 01:36

These modern air conditioners sling the condensate on the condenser. The dust,and anything else in the air plugs the condenser. The dust along with the wet conditions cause mold to grow. Solution, forget the warrenty, my health is more important.I am going to drill a drain hole in mine

Reply

5 Eric Taylor March 8, 2015 at 16:21

I have had many many air conditioners for over 50 years and never had a mould problem until now. This Panasonic split unit has been operating for over 3 years and only now started with mould problems. the mould interferes with the air flow causing much noise like gusts of wind. I tried cleaning the fins and tried your suggestion of running on ‘dry’ but to no avail. The AC service guy has cleaned the fins with special cleaning spray fluid which works for a month and then the problem is back (3 times in 3 months). I have a steam cleaner that I would like to try but I am worried that this could blow the electronics. any idea? Thanks.

Reply

6 Allergy Guy March 9, 2015 at 11:25

Sounds like you’ve found some effective ways to remove the mold, but haven’t yet found the root cause. Mold needs moisture and something to grow in, usually dust in the case of air conditioners.

The moisture comes from condensation so there isn’t much you can do about that other than make sure the fins are vertical so the water drips off and that the water drains straight out of the unit.

Have you checked the air filter to make sure it is preventing dust from entering the unit?

Maybe there is something about the particular model of air conditioner that you have, have you googled mold problem + your air conditioner make and model?

Hope that helps

Reply

Previous post:

Next post: