Stinky Air con. What is the cause?

I notice lately when i turn on the air-con, there is a very foul smell. What is causing that? Does changing the pollen filter fix this??

Change the pollen filter and it should help.

The way to prevent it form happening is to turn off the aircon a few minutes from home and let the air con vents dry out so you don't get the condensation and bacteria living in your vents.

I have had it happen to me in an older car. I gave the vents a squirt of glen20 and then leave it off for an hour or two while I'm driving

My Astra used to do this quite often.

Part of the tray that collects moisture doesn't drain and it goes stale.

My way of fixing that was blast everything on hot for a while to dry it out. If that didn't work, passing a little Glen 20 through the intake vent on the outside of the car with the fans on high would take care of it.

Don't waste your money/time with Glen 20 type products as its only a very short lived solution. The pollen filter needs replacing and its the filter itself that stinks.

They are supposed to be replaced every 2 years by the dealer during your service.

Change the filter and the stench will be gone. Not sure if the Polo's use the same filter than the Golf's do.....but i got the part number off mine and then found an ebay seller with genuine filters for about $25 incl delivery (which was nearly half the price VW wanted to sell me one for).

EDIT - looks like Ryco make them too:
VW Polo page: Search Application : Air Filters, Oil Filters and Fuel Filters :: Ryco Filters :: Automotive Filters Australia

Polo 6R cabin filter: Search Part : Ryco Cabin Air Filter | RCA191C Cabin Air Filter | VOLKSWAGEN POLO :: Ryco Filters :: Automotive Filters Australia

Lots of good advice here except I wouldn't be using Glen 20. Best to use Chlorine Dioxide or run an ozone generator inside the car with the air con on. This will kill all and any bugs and smells in the entire car. Anything else is just covering the smell with a stronger smell.

Mine started to stink a few months ago. Had the filters changed a couple of weeks ago for 2nd year service