Just used one of these in both of our cars to try and avoid Legionnaires Disease` when using the aircon. £4.75 a can in larger Tesco shops currently.
Not a bad idea to treat the system every year or two, takes 10 mins only but do read the can
Dr. Eunos
Thanks for that Taff, I didn’t know it was available DIY 
That is a great price…last time i bought a can of something simular it was over £20…well worth it for getting rid of those smells
Yes it is a good price although I have used the W5 brand item from Lidl before for about the same money, the Holts one has a nicer citrus scent though.
It does need to be fully vented afterwards before you jump in and drive the car again, even then have the window open or you can easily have a coughing fit…