car heating not working

[treeman]

I'm trying to find out why the heater matrix in my car is not blowing warm air into the car. I have just finished putting the cylinder head back on after replacing the head gasket to fix coolant loss.

I've refiled the coolant and bleed the system but still no joy. The inlet and the outlet hoses are hot/warm but no hot air, only cold air.

Could there still be trapped air in the heater matrix or could the problem be with the water pump? How can I check these possibilities.