DIY Automotive Repair Project: How to Fix a Stinky Car Air Conditioner

When I was a cash poor college student, there were a lot of car maintenance and repair jobs I had to learn to do myself. I can change my own oil, install new brakes and even fix leaks. While I now pay someone to do most of those jobs, there are a few automotive repair projects I still choose to do on my own. My recent experience with a stinky air conditioner in my car gave me an excuse to dust off my automotive repair skills. Here is how I fixed my stinky car air conditioner.

What is That Smell?
If you have a stinky car air conditioner, you will know it. The smell is especially strong when you first turn on the air conditioner and permeates every inch of the car. The smell is similar to tennis-sock odor or mildew and is caused by bacteria, mold and fungi that grow in the air conditioner evaporator core, condenser hose or in the pan used to collect water.

These microscopic organisms grow because as the air conditioner is used, the cold air causes condensation to form that then combines with contaminants such as dirt, pollen, dead insects, pet hair, nicotine and tar from cigarette smoke and plant and animal debris. If the condensation doesn’t drain properly due to a clogged tube or if the unit isn’t allowed to dry out completely after each use, water can become trapped and stagnate. This allows harmful bacteria and mold to grow and cause odor.

A smelly car air conditioner should not be ignored; where there is odor, there is mold. The mold spores are easily inhaled by the occupants of the car causing allergies, sinus infections and asthma complications. Mold can be especially harmful to small children and anyone with a compromised immune system.

How to Disinfect and Deodorize the Smell
The first step in this automotive repair project is to disinfect and deodorize the car air conditioner. There are several odor neutralizers on the market that you can spray into the air conditioning vents or directly into the core. If you spray a product into the core, it is necessary to first drill a tiny hole into the top of the plastic heater box under the hood. If you don’t want to go that route, I have had good results using a combination of Lysol disinfectant spray and drying out the car’s air conditioning unit.

To disinfect and deodorize, set the car air conditioner to the recirculate setting. While the air conditioner is running, spray Lysol down under the dash where the front passenger’s feet would be; the Lysol will be sucked up into the unit. Repeat this several times a day for a few days in a row. This will kill any odor causing bacteria. However, you should take steps to dry out the car air conditioner after each use to prevent the problem from recurring.

How to Dry Out Car Air Conditioner
To dry out your car air conditioner, turn off your air conditioner at least five minutes before you stop driving. Then, turn the interior fan to full speed. This will help dry out the entire system. Another way to dry out the system is to set the air conditioning to open circulation a few minutes before turning off the car. When you turn off the car, leave the controls set to open circulation mode. Before restarting the car, turn the air conditioner off so that the air compressor doesn’t activate when the car starts. When you turn on the car air conditioner, always leave it set to outside circulation for a few minutes.

How to Clear Clogged Drain Hose
If you have deodorized and disinfected the car air conditioner, are allowing it to dry out after each use and are still having problems with a bad smell, the car may have a clogged drain hose. Another clue that the drain hose may be clogged is a wet spot on the passenger side floor. This is another automotive repair project you can easily do yourself.

To clear a clogged drain hose, look under the hood and locate a short hose coming out of the firewall on the passenger side. The hose is usually L-shaped and points downward toward the ground. This hose should be open and clear, allowing water to run out onto the ground as the air conditioner runs. If you are running the air conditioner and there is no puddle of water after a few minutes, then you most likely have a clogged hose.

To clear the blockage, use a chopstick, knitting needle or piece of wire coat hanger and poke into the hose to remove any clogged debris. Then run the air conditioner for a few minutes. If the clog is gone, you should see a puddle of water on the ground under the car. If you don’t see a puddle, repeat the process until you have removed all debris from the hose and the air conditioner can drain freely.

People also view

Leave a Reply

Your email address will not be published. Required fields are marked *