97 tahoe heater problems

Tahoe heater will not get hot.Changed to a 195 degree thermostat.Checked hoses going to the heater core,they are getting hot.Today i back flushed the heater core thinking this might help but it didn't.Could this problem be the heater control knob.Also the actuator that connects to the 2 hoses going to the heater core was leaking replaced it,still not getting hot only warm.Has anyone experienced this problem?Thanks in advance

Also truck has a brand new radiator.