The temp valve that opens and closes the hot air intake flap vacuum can thingy is broken. Does anybody know at what temperature it gets hot air? It's failed in the 'cold air position' so I've blocked off the vacuum feed to it, but I noticed a bit of carb icing on the right hand carb manifold, and slight hesitation. Am I ok to temporarily force it into the 'hot' position? Or will this cause over heating issues? Oh its a 2ltr T4.