I flushed my line and radiator on my dodge 2007 ram pickup truck.the heat in my truck is blowing warm air,after warming the truck up for 20/30 minutes, is it my themastact?
Did you have the condition before the coolant flush? Did you bleed the system properly when filling?
Those trucks are known for damper door actuator issues. Have you heard any weird clicking in the dash area behind the radio?
If you did not have the issue before flushing the system it's probably not a damper door issue. In that case I am with Tom about making sure you blead all the air out of the cooling system.