I verified the blend door was working by cutting out the panel behind the glove box and drilling a 3/4" hole into the box and I can look in with my MAG light and see the door opening and closing when I turn the temp up or down.

All the heater hoses seem to be hot. With an infared temp gun they are 130-150 at the surface of the metal T's, So I would say the heater core is getting hot water, I heard the Water pump may have been rusted or coroeded so I bought a new one and pulled the old only to fine it looked just as good as my new one so now what??? What else could it be.

The fluid levels were good the blend door and actuator work the water pump is good, it doesn't overheat, I just get luke warm to no heat in the front or rear of my 2000 eddie baurer expedition with climate control.

 

It's the thermastat! If your hoses and stuff are at only 130-150, once you blow cold air across them the temp drops alot= luke warm air

My 99 Expy, I put a themp probe in the vent, and with my auto set to 90 it blows 164 out the vents!!

With you stat full open, the water isn't getting heated up enough before it's getting cooled down again... it's flowing through the block too fast! I bet if you look at your temp guage it's on the low side as well.

Drain the fluid again, take out the three bolts that hold the stat housing on top of the intake hooked to the upper hose. Pull off the housing pop out the stat and I just about bet money that it's stuck in the open position.

 

a bad water pump would be over heating, not under cooling. I agree start with a thermostat.

You could have air in the lines at the top of the heater core causing the heater core to blow colder, but if the whole truck radiator hoses, and radiator are "cool" then this isnt your problem

 

Ok, I swapped in a new Thermostat today and topped off the fluid levels again and put about 5 miles on it brought the engine up evenly between the H & C and still no heat out of the dash. What else could it be.

Actually seems I get warmer air if I set it to 70 than 90. But I can see the blend door opening and closing as I change temps. Is there more than 1 blend door in there? I know my Cherokee has 3 passenger, Driver & recurculate.

Is there a diagram of the HVAC system somewhere online?

 

Could different brands/ages of antifreeze gel up the heater core? I did put some zerex that was about 5-10 years old (new still on the shelf in my garage) a few months ago to top off the system and I didn't think about it. But it was typical green and the stuff I mixed it with was orange or red.

Could that be the problem.

 

Change the heatercore inlet hose.Their is a steel sleeve in it that gets pluged up or slides up to the curve in the hose and blocks the flow of coolant to the heatercore.

 

I KNOW THIS IS A VERY OLD POST BUT i THINK YOU MIGHT HAVE SOLVED MY PROBLEM. I ALWAYS WONDERED IF THAT COULD BE MY PROBLEM