The force and volume of coolant entering the heater core is not enough?

Hi,

I'm a bit confused. You indicate little coolant flows through the heater core. Also, there is no restriction when you blow compressed air through it. That is an odd one.

If you turn the heater on high, start the engine, and allow it to reach operating temperature, do both heater core hoses get hot?

Also, the air temperature entering the cab is controlled by the air mix door. Have you checked for proper operation of the air mix door actuator? Additionally, on some of these vehicles, they used an air mix cable rather than an electric actuator and those vehicles also have a heater control valve.

If you look below, I attached directions for adjusting it. See if these things are located on your vehicle and let me know.

Take care,

Joe

See pics below.