04 1.9CDTi Heater only blows hot air. How do i fix - sootyville
I was happily driving my Vauxhall Vectra 1.9CDTi 04 reg. along yesterday and after about half an hour i noticed that the car was getting warmer. I turned the heater onto cold only to find that it was already switched to cold. The temperature gauge was fine and i cannot see any other fault. Basically the heater blows out hot regardless of what it is switched too. Any idea as to what i can do to fix this please.?
04 1.9CDTi Heater only blows hot air. How do i fix - Dynamic Dave
Just had a quick search around vectra-c.com for you. Not sure if the following helps or not?

forum.vectra-c.com/showthread.php?t=54271
forum.vectra-c.com/showthread.php?t=36766
forum.vectra-c.com/showthread.php?t=41212
forum.vectra-c.com/showthread.php?t=18433

They all pretty much point to the same thing - A faulty servo that is accessed by removing the glovebox.