Hi, i have a 2001 MK4 golf which has recently had parts of the cooling system replaced recently. Since the work has been completed my heater does not work properly (i.e it blows air but the air is outside temp. Another fault i have noticed is that the radiator temp gauge on the dashboard stays on blue (cold on the left side) regardeless of how long you have been driving the car. This temp gauge problem occured after the cooling system was fixed. Any ideas what may be wrong?

Also! the drivers side window opens fine, but when you use the automatic close (i.e pull to close and let go so it closes itself) the window gets just past halfway up then stops and then reopens itself. Any ideas?
thanks in advance