Heater blows cold till I restart

[Hdokie]

05 Silverado with climate control. Heater blows cold air sometimes unless I restart it. Adjusting the controls does nothing Sometimes on restart the fan doesn’t blow at all.  

 

I think it’s a blend door actuator. But which one ? I hate to throw parts at it. 

 

Any help would be appreciated

[sefiroxx]

Verify fan is working. Air flow must come out of some vent.

[SouthPawCO]

What might help is having the vehicle in park, windows rolled up and no background noise. Adjust the HVAC unit and listen to the actuators moving. On my '05 Silverado, I can hear the actuator moving when I adjust the temp. I have always been taught when adjusting the temp, turn the blower motor off so the actuator is not fighting the moving air which will prolong the life of the actuator motor.