I've had a look at the Topix 'Description & operation' for the climate control, plenty of info regarding the ram air and recirculation strategy, the outlet flap control and the blower motor. What I can't find is where the cabin air is drawn from in recirculation mode - the reason?
Well, with other models, it's easy to remove the pollen filter and direct the aircon debug sprays into the ventilation system that way, thereby ensuring the majority of the stuff gets where it needs to be to do any good. With most cars, the spray is generally left to discharge into the cabin which mostly coats the headlining and other trim with not much seeming to get into the heat exchangers or ducting.
Short of smoke testing the heater box to see where it's being drawn in, does anyone have any ideas?
Thanks.

Most I have seen have said to put the can in the rear footwell and leave the doors closed and HVAC on recirc for around 15mins... I had a smelly car once and put it in the front foot well pointed up towards the bulkhead which is where, I believe, the recirc draws air from, and the car stunk of the cleaner for weeks...

I suppose they make it so the concentration from the whole can is enough to do its job without trying to "supercharge" the application....  Pete
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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

I've been through Topix again, still no real clue although I do agree that it has to be at the sides of the heater box as that's where the actuator & flaps are. I think I'm going to take the centre side cheeks off in the footwells and point a can each side up the side of the heater box with the fan on 50%, recirc. on manual, distribution manually set to 'everything' and the temp on whatever the ambient is, that way it'll clean both the heat exchanger and the evaporator. Yep, it'll smell a bit 'chemical' for a few days but it'll be better than the current smell which is as mixture of 'stale cigar smoke' and 'child'...

The one we used to use at work were very good, it was basically a foaming aerosol with a long plastic tube which you could push down vents to get to the condenser & heat exchanger, the full can was sprayed into it and allowed to reduce for 5 mins, then the heater was put on a low fan and temperature near ambient for 10 mins, it seemed to work very well and there was no residue on the headlining or trim. There was always a lot of muck coming out of the condenser drains so It seemed to clean as well as debug.

It's drawn from the pollen filter housing behind the glove box.

You can see this if you:
1. Have re-circ switched off
2. Drop the glove box down
3. Switch re-circ on
4. Observe the top of the housing open up to suck the internal air in Kev

2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey

L322 not L405 matey!

Whoops! Sorry!  Kev

2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey

No worries - it does get a bit confusing sometimes as there is so much crossover.