Heat from blowers only while moving

[ToyoTayto]

Well lads, sorry if this has been answered already can't seem find it. Driving a 2006 d4d Corolla with A/C. Only noticed this evening, I threw on the blowers in the car and there was only cold air, temp slightly under half, all the dials working can hear the difference. When I'm driving though everything is fine car is absolutely roasting. 

I took out the egr valve to clean it the other and lost a small bit of coolant disconnecting the pipes, so I'm thinking a slight air lock? Can someone explain how to purge the system properly?

if you think it might be something else that it might be 

thanks

[roks]

There are some youtube videos that show how to purge air. Basically this tool fits in place of the radiator cap, then running the engine until the thermostat opens and all air is out. I can best describe this tool as square bottle cut in half. Coolant will overflow into this when it expands.

I improvised this tool with a big funnel, cutting the bottom until it fits the radiator cap and the use insulation tape to make it water tight.

[oldcodger]

It suggests there is somwething wrong with the heater control valve; prehaps the forwards motion or higher revs when drivng allow the hot water though even though the valve is in the cold position.

Think your model will be by a wire from the control knob to valve, it could be faulty/loose ?