how do i fix heat in 1999 ford ranger 2.5?

Question

replaced thermostat already water flows thru heater core but still no heat

Answer 1

If both of your heater hoses are equalty hot after the engine has warmed up to operating temperature, then you have flow through
the heater core and have a problem with the ducts in your plenum
chamber that holds your core and your evaparator if you have a.c.. If one heater hose is a lot warmer than the other, you have no flow and a cloged heater core. You might be able to back flush
the core if it was cloged by running water through it by disconnecting the htr. hoses and using a garden hose