I know that a new heater valve will probably solve the constant heat issue. However the squeak seems like a potential headache.
In the past my Mk2 Polos fan needed some lubrication but internally on it's bearings. This involved removing the fan and using a long nozzle of an aerosol to get through the fins of the fan to the bearing.
I suspect the Scirocco is similar. Before I even start is there a way I can lubricate the fan without removing it? I've tried spraying the visible spinning parts. I see some people have ended up replacing the whole fan which doesn't look fun from the scuttle side

