Technical 100hp Fan issue?

[The100hpGuy]

This is a strange one... Heat decides to only come out of the vents when the fan speed is put up to max (after hearing a clonk) and then you are able to lower the fan speed... But then if you go too low on the fan speed you hear another clonk to which only cold air comes out... All of this doesn't matter what temperature you set it, it's either cold on a low speed or hot when the speed is put up to maximum (even when the air con is switched on).

Have no idea what it could be, any ideas?

 

[irc]

Theorising here, but sounds like one of the flap control gears has stripped some teeth. The extra air pressure on high is probably opening the flap to where it has some teeth left.
Got the same on my Eleganza but have been too lazy to fix it so far. Occasionally makes a tapping noise when fan speed is lowered, which I guess is the flap opening and closing in the airflow.
Was waiting for warmer weather before stripping it out and investigating further.
Not sure if the parts are available individually, but I'm sure someone on here will know.

 

[The100hpGuy]

Thanks, that's definitely a good direction as to what the problem could be.