Corsa C Heaters Cold

[max1958]

heaters cold even with a new thermostat fitted it uses no water not boils up a bit milky muck in rocker box

[BRIGHT SPARK]

It may be an airlock.

[SpikeyBush]

Is the knob on the dash faulty? Wouldn't worry about that small bit of froth this time of year, especially if it is used for lots of short journeys. If it was like the head on a pint of Yorkshire bitter it would be different.

[TWR]

If its a diesel,it will take a while to warm up, when the car is running, feel the heater pipes under the bonnet ( are they hot) if not "Air Lock) other than that, back flush the Rad.