Mould and smoke smells in the air conditioning

Another annoying issue is when you run the air conditioning (AC) and can smell mould or tobacco smoke. The mould smell comes from water that has not dried from your AC's evaporator system before turning it off after use. (Note that turning the AC unit off, with the fresh air running through the system about 5 mins before you stop driving helps prevent this from happening) The water in the unit is helping bacteria and mould grow within the system. To remedy it can be a huge job, involving removing and cleaning the entire system out of the car. But the good news is that it can be treated and most times removed, and the instructions below should help to treat the internal ducting, fan blower, evaporator and heating elements in the car.

First step is to find and the AC’s air filters (most later model cars have one, older cars not always). They are in different areas with all cars, usually in the passenger side foot-well, but you may need to consult your cars' handbook, or ask your local car dealer/mechanic where it is. These filters remove a lot of the organic particles and pollutants from the air and hold onto them, creating a great place for mould and other bacteria to live in over time. Order a new filter, and once it arrives, follow the procedure below.

Park the car outside in a well ventilated area in the shade. Pull the handbrake on, put into neutral gear if it's a manual, or “Park” for an automatic. Remove the old AC filter (you will replace it after all the following is done). Start the engine and turn the AC on full speed, making sure it's switched to the fresh air or outside setting (not recirculate). 

Locate the fresh air intakes for the AC/ Heater.

Locate the air intake vents for the AC in the front of the car, sometimes under the bonnet, along on the cowl panel, just under the front windshield. Spray about 4 to 6 sprays of Pong-Go into these intakes, then hop in the car to make sure you can smell the Pong-Go coming through the vents inside. Do this at least three times, switching the air direction (if possible in your car) from blowing into your face, then to the feet/ footwell area and finally the windscreen, waiting 1 minute between applications. 

After having run the AC with air from the outside, switch to recirculate. 

Spray Pong-Go into the cars internal recirculating air intakes, usually found up under the dash. 

Switch the AC unit to recirculate and spray the Pong-Go 6 to 8 times into the cars internal air intake, which will most likely be around the foot-wells, then close the car doors and leave running for 10 minutes. 

For the final Pong-Go treatment, turn the heater on.

Then switch the AC off and turn the air directional switch back to your face, then turn the heater on full heat. Spray as you did previously, two to three times in the front cowl air intakes again and leave running with the doors closed for 5 minutes. Wipe any Pong-Go residue away from the vent areas with a clean microfibre cloth. Turn the engine off. Put the new AC filter in and you're done, if the smell is still there, repeat the AC/Pong-Go treatment till you're happy it's gone. We recommend you look at doing this at least once every year, including replacing the AC filter, or if and when any smell appears while the AC is running.