Which B7 Heater Motor?

[mountainmile]

Back again for the hat trick heater motor replacement unfortunately

I know that with regard the passenger side mounted ones.....
When the green one went I had no windscreen defrost
When the red (some say brown) one went I had different temps between left/right

Now I seem to have constant flow out the 2 side ones (regardless of temperature setting)

So im wondering (1)what does the passenger side black motor do....and (2)what do the ones on the drivers side do ? (haven't psysched myself up to pull that side apart yet)

Thanks in advance
(2005 RHD B7 Saloon)