My 2004 XC70 has a musty smell when a/c or fan is on. The smell started this summer. I checked both air filters, they look good.

1 filter. You could also try spraying deodorizer into the cabin air system intake near the hood and windshield from the exterior.

What kind of smell? Sweet like coolant or a musty, decomposing like smell? If sweet like antifreeze it could be your heater core if musty/mildewy or decomposing like smell try replacing your cabin air filter.

Never turn-off the car with the air on. Turn-off the AC and allow the fan to blow-out the cold air for 30 seconds or more. This will prevent that 'musty' 'stinky' smell from occurring in your vent due to condensation.

If the car is 'slow' to turn-over, then your car battery may be failing....

Tallon41

Need to change the cabin air filter, when it gets old it will produce an awful musty smell

Sounds like it's time to replace your cabin air filter. These tend to smell over time especially in vehicles where the owner smokes.

It sounds to me if you are having a "musty smell" then you might have a problem with your condensation drain line for you a/c system or a small leak on your heater core. If it is plugged then water will collect in the vent system causing a musty smell from the water not draining and if there is a small leak on the heater core then coolant can collect in the vent system. I would run the a/c on a warm day and look for water draining from the vehicle around where the dash is located to check the drain line. As far as your air cabin filter most are located behind the glove box. You usually need to remove the glove box to get to the filter.

The drain should go through on the passenger side under the dash....you might need to replace your cabin air filter.

There is a feature called afterblow. It was active on a variety of years and could be activated by the dealer when/if the customer was experiencing a musty smell from the air conditioner. Typically it will come on for about 3-5 min about 20-40 min after the car was shut down while the a/c was run.

I am having the same issue. I changed the cabin air filter (Located under the passenger side dash - remove 4 small screws) and still cannot get rid of the musty / urine smell. I have tried all the "over the counter" ac unit sprays and I also took the car into a place that used some kind of a fogger inside the car.Unfortunatly, the smell returns. Let me know if you have any luck.I have tried all the recomendations such as, Lysol, bleach, fogger and still nothing. I believe the AC unit needs to be exposed and cleaned before the problem is resolved.Good luck!

Have you replaced the a/c air filter under the dashboard? If not get one from the dealer or even a napa (napa part # is wix 24902) The filter is under the glove box. 4 eight millimeter screws hold the cover in place. You will be quite surprised at the quantity of mung these filters collect. I replace mine every two years regardless.