So, after further investigation, all 4 holes as clear as they can be, ie not blocked, we checked the function of the flow of warm air to the windscreen to find it almost non-existent, other settings were fine.
If someone can nail down likely cause and how to fix, as ever eternally grateful!
P
PS Also noted my rear screen heater aint working either ......the screen has been replaced, where are the wires routed to supply the screen's heater element?
PPSS AS I've not got the manual for car whats the button above the EC button with two vertical wavy lines for?
Thanks Lostkiwi, where are the vacuum pipes to fix, starightforward or part dismantle dashboard?
P
In the area next to the ECU there is a vacuum distribution block (assuming same as r129). These have a habit cracking and leaking. A dab of epoxy will sort it in no time.
From there there are a raft of vacuum lines one of which goes into the vent control block behind the glovebox. If there are any vacuum leaks in the system the whole lot plays up.
As I say though - normally the failure mode results in windscreen vents working along with the two side vents but you can't redirect it anywhere else.
Suggests you may have moisture somewhere in the car.