Has anyone cleaned the air conditioning evaporator on an Octavia 4 (2021, 81 kW, 1.0 TSI)?

Last winter I had problems with the heater core, and it has since been replaced. However, I can still occasionally notice a musty smell coming from the evaporator.

So far, I haven't been able to figure out exactly where the evaporator is located or where the cleaning foam should be applied. Is it possible to access it from underneath through the condensate drain and clean it that way?

Does anyone have a clear diagram of the entire HVAC system layout?

Thanks in advance.

Just general comments really, I fussed about this when I had my 2000 VW Passat 4Motion and at that time, maybe round about 2005, the "AC bombs" seemed to have a long tube and that needed feeding into the air plenum box - but I didn't actually complete that task!

By the time that I got round to re-visiting that task with later cars, all the "AC bombs" had done away with the long tube, and the plan was now to just start up the car with all windows closed, turn on the AC on recirc, place the bomb on the floor in the rear of the car, and set it off, close doors and leave the car for a certain length of time, then open the door, switch off the engine and remove the now empty bomb container - job complete.

I've used that method but removed the pollen filer first then closed the pollen filter cover, and fitted a new Frecious pollen filter after running that AC bomb.

Edit:- sorry that I didn't answer your question exactly, but in all these cars the AC evaporator is inside the cabin heater box, along with and beside, the heater matrix. So, that is a closed mainly plastic box and getting into that area in a way that allows full access to the evaporator - will be a very big job, so all you can try is to use one or two of these "AC bombs" and that should kill the bugs and most of the smell.

Edited Sunday at 14:562 days by rum4mo

Thanks for your reply! I've used a similar product once before, and it did help – the air in the cabin definitely smelled fresher afterwards. At the same time, it felt like the strong fragrance was just masking the problem, and I can't imagine it actually removes mould from the system. I was hoping there might be an unscented product that could properly clean the evaporator. I understand now that it's not that simple.

The market has determined that some kind of fragrance is expected to mask the odour of the solvent carriers and fungicide / bactericide / biocide. Additionally, there is a slight risk of allergic reactions to some of these substances. But they may claim a standard of effectiveness - for example EN1276 specifies 99.99% death to bacteria and microorganisms. EN14476 is another standard relevant here. Best to treat the car and then leave it overnight. Plenty to choose from.