Originally Posted by hoyleyboyley
Bleed he system by getting up to running temp and opening the bleed screw near the filler cap, taking care as it is all very hot (105c) and let the air fizz out.
I wouldn't do this if I were you. The valve on the coolant expansion tank near the filler cap isn't a bleed screw and doing the above will simply de-pressurise you cooling system, which isn't good.
The bleed screw is in one of the hoses connected to the heater solenoids by the bulkhead. It would be worth checking the two bleed hoses (one from radiator, one from temp sensor manifold) for flow into the coolant expansion tank by looking inside the expansion tank at fast idle with the engine cold. Replace the cap before it warms up too much - or at least remove and replace the cap when it is stone cold to allow it to repressurise when it warms up again.
You could then check the hoses into the heater control solenoids at the bulkead to see if they are warm and bleed air out of the bleed valve here if necessary. Set the heater controls to maximum.
If warm water is getting to the heater matrix, but warm air isn't coming out then it could well be electrical. You have climate control as I do and mine seems to have mind of its own sometimes, although more with the fan speed than the temperature and which vents the air comes out of. Could also be that your heater matrix is blocked, or the control solenoids have got stuck if it's been shut off (full cold) over the summer.
p.s. mine still blows cold(er) air out of the face vents regardless of whether the knurled wheel is set to red or blue. It isn't noticeable at first when the car is warming up as the 'auto' setting on the distribution blows warm air firstly to the screen and then to the feet as the car warms up, then when it has reached the desired temperature, it decides to let some air out of the face vents, which in my car always seem cold or at least colder than the other vents. I tend to close them because of this.