Sorry I wasn't clearer. There is a motor driven hood or flap on top of the fan assembly and this opens when the re-recirculate switch is operated. This is where the cold air comes from when it is opened. Very little air comes out of the windscreen, foot well, face level vents, with any settings. I removed the pollen filter and this makes no difference either. i have also checked for blockages as far as possible. Certainly there is no debris that I can see at the external intake.
For all the world it seems as though the fan is blowing when it should be sucking.....As though VW makes both kinds and I have fitted the wrong one!!!
And yes, it has occurred to me that I have lost the plot!!!
That's interesting then! But presumably it
used to work OK and you haven't changed the fan? I'm not familiar with the Touran, but pretty much all the cars I've seen, use centrifugal fans for their heaters. The blades look like a cylindrical cage with fins on, rather than the "propeller" type fans for cooling the radiator. If the wires are the wrong way round, a centrifugal fan won't "suck". It will still "blow", but a bit less efficiently than if the wires are the right way round (because of the aerofoil cross section of each blade facing the right way when it's rotating in the correct direction).
The recirculation flap either allows the fan to pull fresh air in from outside the car, or, (if the flap closes that inlet off), it forces the fan to take air from somewhere inside the cabin (usually behind the dash) and blow it back into the cabin. Useful either when there are fumes outside, or when the car is very hot and you're then passing the same air through the air conditioning evaporator several times, getting cooler each time, rather than pulling hot air in from outside the car.
Somehow, it looks like when set to recirculate, everything is working fine, but when set to pull fresh air in from outside the vehicle, there is something preventing the air from coming in. Has the car been laid-up for a while? Is the mouse nest somewhere in the ducting? If you haven't changed anything, it must be some deterioration, rather than anything that could cause it to work differently.
Apologies if any of this is telling you stuff you already know!