Low or no heat from heater - blower runs on 2005 Buick LeSabre

Little to no heat from heater; blower runs; started before I changed thermostat - code was set; have tried to bleed air at thermostat valve.

Asked by for the 2005 Buick LeSabre
it is possible the following happened:
1. switch is not working
2.blend door is not working (possible actuator)
3. electrical problem

this is a job for a technician to run down. these controls are all electrical and any can cause this. hope this helps!