Very curious. I can't say I've suffered with cold air coming in, but the lack of air I think is simply to do with orifice size (so to speak, doctor...).
When I am demisting I nearly always us the aircon (but not on recirculate), as recommended in the handbook and it clears in seconds even if I have been sitting in the car a long while and it is really steamed up (ooer!). That's ok if you've got aircon, of course.
The screen vents are obviously longer and thinner than the big fat vents in the center console thus I don't believe the air feeds with as much oomph (can't think of a better word, sorry.). And when you set it to screen it also feeds the little dash vents on the very extreme right and left that clear the side windows for view from the wing mirrors (I think...) so the flow of air is dissipated somewhat (probably wrong spelling of an incorrectly used word here, but you get my drift, I'm sure.).
And just increasing the fan speed I have found doesn't really help. It's like trying to get two Margate girls through a doorway. No matter how hard you push, it ain't going to work, the gap isn't big enough.
A couple of things to try to see how quirky the heating system is on the Multipla.
1. Set the fan to hot, and the direction to just your feet. Now put your hand over the passenger floor heater exit thingy, then do the same on the drivers side. Is it me or does more hot air come from the passnger side? (It use to when my last girlfriend sat there anyway.....)
2. Set the fan to hot and then facia vent only, so it belts out in your face. Open all the facia vents, the left and right round ones on each side, the middle top one, the middle left and right one and finally the middle lower one.
Right, close the extreme left and right ones. You will feel a definite increase in flow through the centre vents. Then shut the bottom most centre vent and then the top most centre vent. Each time you should feel and increase in 'pressure' from the remaining vents. Finally shut the left vent on the centre facia vents so just the right one is open. The force that the air is coming out is quite strong now. All the flow is through one big vent. It's like choking a hosepipe, same water pressure, but more squirtier!
Seems obvious, I know but when I want to warm me up quick I shut every vent except the centre right vent and the extreme right dash vent and aim them both at me. It's amazing how quick you warm up! Unnecessary open vents weaken the flow of air, I think.
Incidentally, I have found that Myrtle's heater gets slightly hotter than my old uglybug did and it warms up noticeably quicker. However, she doesn't seem to remain as warm on tick over as Bella did, so it's swings and roundabouts.
And the setting for feet/face is just hilarious. According to the handbook, if the heater is on hot, on this setting, you are supposed to get hot air to your feet and cold air to your face. Well, Bella the uglybug always gave me very welcome and expected hot air through both vents, but Myrtle has a mind of her own, sometimes doing as the handbook says and othertimes just roasting me!
What makes you think I spend a lot of time sitting in my car of an evening, bored stiff? The life of a civic chauffeur!
