The truck is blowing cold air. The thermostat is fine. It has a new water pump and heater core. The a/c is disconnected. The fan blows cold when it is on low but once you turn the fan up it blows extremely cold air. Any thoughts.

This link may help:

https://www.askmehelpdesk.com/cars-t...ml#post2651405

Focus on the heater control valve.

That has been taken out. We think it might be an air lock or one of the doors for the rad isn't shutting.

Look into how to run the diagnostics on your Electronic Air Temperature Control (EATC) System. Here's where I'm coming from:

https://www.askmehelpdesk.com/cars-t...ml#post1999642