Get Rid of Car AC Musty Smell

When you are encountering a musty bad smell coming from your AC, this may be a sign first off that you need to change your cabin air filter. Generally, this is located behind the glove compartment of the passenger side of the vehicle. There are times though after changing this you still encounter a musty bad smell from your car air conditioner. This smell may be caused by moisture building up in your AC system and evaporator instead of draining out of your car like normal and can cause this musty moldy smell.

Step 1. Turn on the Car AC and Select Outside Air.

After turning on your car air conditioner you will want to select outside air as the source of airflow rather than recirculating the cabin air inside the car for this procedure. In many vehicles this is the default and you may just make sure that the button with the shape of a car and a "U" shaped arrow is not selected. You will then turn up the fan speed in order to move as much air as you can through the AC.

Step 2. Pop Your trunk

At this point you will need to pop your hood just for easier access to the air intake grate at the base of you front windshield. Popping the hood gives you easier access to this, and may not be necessary on some vehicles. The grate looks like a honeycomb plastic piece with holes in it to allow air to be drawn in from the outside for air conditioning. This is the area we will be spraying.

Step 3. Spray Lysol

At this point you have the car turned on, AC running at high or full fan speed and you have access to the air intake area at the bottom of your front windshield with the hood popped. You can now take a can of lysol spray and spray a steady stream into the air intake with the AC running.

I would spray this up and down the length of the air intake grate a few passes. While you are doing this it is a good idea for no one to be in the car because of the strong smell of the Lysol for maybe the first 10 minutes of doing this or having the windows down.

What this does is it kills bacteria and any mold that may have built up in the cars AC unit which may cause this smell over time.

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Step 4. Prevention in the future

When you run the AC over time in the summer months you may be smelling condensation that has built up on the evaporator and bacteria and mold may develop causing this smell. To prevent this going forward you can run the cars fan without the AC on for a few minutes, this may clean out some of the moisture building up in the AC system and less moldy musty smells in the future. See below for a video I created showing how to perform this step by step.