I am interested in what you find out! I too am not getting much heat, except my radiator level keep dropping slowly I gotta add more fluid every few weeks, but don't see a drip anywhere!!!???

 

Small leaks will just evaporate or disappear as you drive. Check the water pump or radiator for cracks. Also make sure the oil is not milky as that could mean head gasket leak.

 

This is what I did to check mine and ended up breaking it. The door moved fine and I got great heat and blend. My initial issue was the lack of blending the air, not the lack of heat altogether. When I had lack of heat, it was the thermostat that was bad. Anyway, when you re-install the blend motor, you WILL break the plastic interposer as the motor needs to be reset. The motor will think the door is in one place and will crank it too far and snap the interposer. Only way to fix is with the instructions in the Heatertreater kit. This is how I broke mine and realized then I had to order. It's cheap enough and a quality kit for sure so just FYI. (Actually thought it was the control panel in the dash at first and even bought a used one to replace everything. Mechanic wanted to open up dash for $$$. Couple bucks later, I had fixed it myself with kit.)

 

When we put the garden hose to the heater hose, I let coolant come out the other hose (the one that goes to the pipe on the water pump) then put my thumb over that to keep it full. We kept filling the other hose until we thought we had all the air out of the system. The level at the top of the radiator went down and back up a couple of times and some air came out too so I thought we had nailed it, but really no change.

Moving the temp selector on the dash from warm to cool and back will change the temp of the air, from cool to slightly warm but not hot. We get the exact same results when moving the blend door by hand which makes me doubt the interposer is cracked to the point of causing the problem. If I got different results when moving the door by hand, I wouldn't hesitate to get the kit to replace it. We can hear the blend door hitting its stops (I assume) when we move it by hand. It only moves about 45 degrees from one extreme to the other. Does that sound right?

By the way, the engine reaches operating temp so I don't think the thermostat is stuck open.

 

We will try running water into the core from the other (driver side) hose and see if that makes a difference. Will let you know.