Smelly Vehicle Air Conditioner Diagnosis
There are two separate issues that could be resulting in your smelly cabin whenever you turn on the air conditioning. The first is a dirty/old air cabin filter. The good news about this issue is that it can be a quick fix if you take your vehicle in to the service center and have the cabin filter replaced.Read More: Diagnosing a Leak Using the Puddle on the Ground
However, the other issues it a potentially moldy evaporator case. This happens when water sits in the evaporator case due to a blocked drain. In this situation there is mold potentially growing, and you'll need to bring it in to the shop to have things looked over by a professional. In some situations, you can use a DIY deodorizer to keep your car from smelling, but it depends on the severity of the issue and the smell.