heater problems blows cold air

[ezy]

hi guys

my heater works perfecy if i disconnect the vaccuum line from the heater tap
but as soon as i put it back on it will blow cold air

[hako]

The cold/hot dial may be faulty-
look on the floor near the pedals left hand side and you will see a white plastic lever that the cold/hot dial operates- this may be misadjusted.