Scirocco Register

Hi i have a 1983 scirocco
Im looking for some advice on my heater vents
the two center vents on the dash are the only ones that blow hot air, well blow hot air constantly even if i switch to cold.
The two at each end just blow cold all the time and i get no air at all from the feet or windscreen??
I have also noticed when on hot it blows a good heat when driven but when at idle its still hot but blows cooler

Has anyone got any ideas or had this problem before ?

The two side vents are only ever connected to "fresh" air so they're working as they should.

The top and bottom vents are controlled by the slider controls - are these sliding freely? The sliders are connected to the vent flaps directly by cables - it could be that the cables have come off somewhere - or something else (inside the "heater box" is preventing the flaps from moving. Or even that a previous owner removed the flaps.

I can't think of any reason why it would be cooler at idle - unless the temperature gauge is also showing a reduced temperature?

I do hear it moving when i move it to feet or windscreen but now you mention it one of them is a bit different feeling than the other side but if i do it i bit quicker i can hear the flaps moving or it sounds like they are
And driving today the heat coming out was just worm not as hot as it should be as i took my mk2 golf out for a spin and its alot hotter

What state is the coolant in? Nice and clean or starting to get rusty and sludgey?

Coolant good the guy i bought it off had put the red stuff in not sure if that would make any difference
I have looked on the net about it not much there other than a bypass thing getting blocked that is attached to one of the matrix pipes ? That might be the fault with the heat and i guess i would need to take the dash out to check the cables going to the flaps on the heater box?

There is no "bypass" as such - that's a mk2 Golf thing. The Scirocco (same as mk1 Golf) has a heater valve that is opened/closed by a cable attached to the hot/cold slider. Look just to left of the servo and you should see it floating about - try moving the lever by hand to see if it's stuck.

The red stuff could potentially be the cause. There are reports of red "oat" coolant not working right in older cars that aren't designed for it and forming sludge.

I'd have a feel round some of the coolant pipes as the engine warms up. If it is taking ages for the feed and return to the heater matrix to warm up, I'd look to a partially blocked matrix. Drop the coolant, fill with water and flushing chemical as per instructions on the product you use, thoroughly flush the system in both directions with a hose, then refil with the correct coolant

I'd put money on the constant hot air being a worn out heater valve, replaced it on both cars i've had:
https://www.vwheritage.com/171819809e-h ... o-scirocco

They wear on the inside, so even if you can move it to closed fine, it may still be letting hot water through.
Location is as Mr Brown says, and is really easy to change

Thanks for all the info and help been away on holiday so will be looking in to it now im back
Cheers