Air Con in general - Marc
The ventilation on my Mondeo stinks. When the air con is running it is fine but when you switch it off the car smells musty and like sweaty socks. I've read in various places that dealers can spray some freshener down the vents to kill the bacteria but can you buy this spray at Halfords etc and do it yourself?

I'm a bit annoyed as I've run the air con all year round to try and avoid this apparently common problem.
Air Con in general - flatfour
I have the same problem on a new Saab 93, never had it on my old Passat. saab want £100 for an air con service, Why? and why do some cars smell and others not?
Air Con in general - kithmo
A good blast of high heat will kill the bacteria. Run the car up to temperature and put the heater on full heat, highest fan speed, then alternate the flow between the screen, footwells and facia vents, leaving it on each one for at least 5 mins at a time. Do this for a couple of journeys and the smell will fade. Also to prevent it coming back, when you leave the car parked close the vents (position dot on the air direction knob), this will reduce condensation and hence damp (ideal conditions for mould) and will also reduce misting up of the screen when you first start up. It worked for me (Mk3 Mondeo). Another thing is, Ford's own brand pollen filters filter odours as well as dust etc. some aftermarket ones don't. It may be worth changing the pollen filter as well.
Air Con in general - Marc
Thing is I've done this. Indeed, at the moment if I run the car with full heat on it temporarily eliminates the pong. But it will come back tomorrow.

Until just recently I ran the car to work every morning with the heat on full for about 30 minutes (for comfort) so you would think that several months of this would have killed the bacteria but obviously not.

The car is serviced at a Ford dealer so I presume they will changed the pollen filter as and when scheduled. However next time I'm going to ask for the deodoriser.

Don't have this problem in our seven year old Volvo.
Air Con in general - Cheeky
Peugeot's have this problem too - particulary marked on the 206
Air Con in general - Dave N
Once you have bacterial growth on the evaporator, no amount of hot/cold/recirc/on/off etc is going to get rid of it. Also, if the drain is blocked, it will be with you forever.

If you take a look at www.autoair.co.uk/smells.htm you will get some more info.
Air Con in general - KB.
Looked at www.koolspace.net it included the following......Q: Why can I smell a \'musty\' smell inside the car when I turn on the aircon? A: This is due to the build-up of mould and microbes on the evaporator. It can be cured with a micro biological treatment of the evaporator unit during the annual health check.

KB.