Heater not blowing hot air

Did you bleed air out of system? Is coolant full? Is your blend door actuator switching from cold to hot? Did you flush out your heater core? Is van overheating? I ask because if you have a blockage then hot antifreeze is not circulating through system and getting to heater core. Do you have any leaks? Holding pressure?

It was the water pump. But thank you for your suggestions. Have a blessed day!

my van is not over heating I flushed the system put new thermostat it blows warm air as long as you keep the rpms up but not at an idle

You still have air in system.