hi All,

i have commodore VY 2003, the thing i noticed that changing heater knob either cold or hot, the heater tap dont move. i checked and found there is no vacuum while changing the to heat or cold at the dash temp knob. the amaizing is that the heating system looks working fine and i get hot air when i turn the knob to hot and when i turn to cold, i get normal air..

any body please tell me wether its a fault , and tell me where to check and the cause of problem...