Hello,

I have a 1997 xlt 4x2 ranger that I have had for several years. The heater went out years ago and I have been trouble shooting it since. I have flushed out all the hoses, heater core, radiator, and reservoir with no luck. I have also replaced the heater control valve and radiator cap as well as blead the air pockets out. The inlet hose to the heater core is hot but the outlet is not. I have flushed the heater core several times and the water runs smoothly and clearly. the blend door is also is also in the correct position. At this point I am at a loss and could use some direction.

 

If only one hose heats up then there is no flow thru the heater core, if garden hose water flows thru it then coolant will as well, so either by-pass valve is stuck closed, but neither heater hose should be warm, or the core is plugged

So there is an error in the testing, based on heater hose temp only

The hose that comes out of the intake is the OUT to heater core
The hose that comes out of the water pump is the RETURN from heater core

The heater core has no In or Out connection, it works either way, so either hose can go to either port