Heat does not work. coolant level ok and temp is ok

Might try checking the temp blend door operation or the temp blend door actuator. If all good there perhaps the control head itself is faulty.

Check to see if the temp,door is moving when you change to hot on the selector .Then replace the thermostat,and if heater core is not letting the hot water flow threw it,remove the heater hoses going to the heater core,and flush them out with a water hose.