no heat for windscreen demister

[clutch]

hi guys, one of my roady items is there is no hot air going up to the windscreen to demist it, what could be a possible cause of this?

just a lose vent tube? or something more serious?

cheers

[DerekP]

Are you getting hot air through other vents? Is there air flow to the screen but just no heat or nothing comiong out of the screen vents at all?

[ari666]

that vacuum switch. grrr

oh wait, VH or VK? the vh doesnt have a vacuum switch does it?

[Darren_L]

vh doesn't use vacuum, it uses those pain in the arse metal rods/linkages
can you get hot air to the floor ? If you can, then the heater core is still working.

you probably need to remove the vent control slider and make sure the metal rod is still connected to the demister control link on the heater box.
they are a fiddly, shit of a setup, but you'll know if the rod has popped out as soon as you pull the vent control unit forward.

if that is connected, then chances are there is a problem with the demister vent flap inside the heater box. Sometimes the hinge pin falls out, or the foam seal rots away. Also the ducts that go from the heater box to the demister vents sometimes don't seal properly either which means the hot air escapes the heater box before it gets to the demister.

the VC-VH ventilation system has to be the worst design I've ever seen. I've got to pull my entire heater box out AGAIN, because I can't get bugger all heat to the demister or the floor... yet I have a near new heater core. If it wasn't such a drama, I'd swap a VK-VL system into the VH

[c2105026]

when i got my VB the first thing I had to do was replace the thermostat. I got no heat whatsoever, and the car always ran cold. check your thermostat?