no heat

Your temp gauge is where it should be, the heat problem is more likely the blend door actuator less likely is a plugged heater core. When you move the heat control from cool to hot can you hear something move under the dash, if not suspect the blend door

Possible air lock. Purge air out of the cooling system.

You're not overheating so the cooling system is working, try squeezing the heater hoses and see if they feel hot. (oh BTW, warning: they might be hot.) If they're hot then the heater core is getting flow, then it's likely the blend door as Mike suggests.