Q: Moldy smell from AC at startup

asked by on

I've seen lots of post on forums and websites about potential condensation collecting inside the ducting that is harboring microbial growth which is producing that smell.

Now my question is, why don't I smell it when I keep the AC off and ramp up the fan? This question may lead to the following: how do I find where the source is? Is the only way to thoroughly clean out this mess by taking the ducting/trunking out and clean/soak? Is it doable? I'm skeptical about those off-the-shelf sprays. I'm looking for a solution that doesn't just mask over the problem but getting rid of the problem for good. What are your views?

Hello, thank you for writing in. The best way to remove a moldy smell from your vehicle’s air conditioning system is to replace the evaporator. This is a very time consuming and expensive repair, but is the only way to fully remove the mold. I would recommend enlisting in the assistance of a certified professional to have the evaporator replaced as the dash must be removed in most cases. This could result in many screws and bolts missing or in the wrong place. It is also important that the air conditioning system is evacuated prior to replacing the evaporator to ensure that no refrigerant is released into the atmosphere. If you find that the mold is at a more reachable place, you may be able to get rid of it on your own. Here at YourMechanic, we can have a technician come to your home or office to inspect this smell for you, and make or suggest the necessary repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Moldy smell from AC at startup

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: BMW 640i hazards came on on automatically & car won't start &

Your car may be in anti theft mode. In some cases the alarm may not sound, but the flashers will go and the engine ECU will lock down to prevent the car from being driven. It might be that the...

Q: What Dangers Are Caused by Hanging Things From the Rearview Mirror?

The first danger that should be considered is the fact that items on the rearview mirror are a distraction. Depending on the object they can partly obscure your view. Visibility is a main concern as well as depending on the...

Q: Doing less MPG than before and I sometime feel heavy slow during driving

This may be related to what is called a mass air flow sensor. This is a unit that monitors the air intake as it is mixed with fuel prior to being injected into the motor. This unit sends a signal...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...