Just like the title says, the heat is Luke warm to cold. I've researched all the posts and did everything I know to do. Here is what all I have done. Flushed cooling system and then flushed heater core separately. I flushed it both ways, Crystal clear water and high flow both directions. I replaced the thermostat when I flushed it with the stock 195 thermostat. The in and out hoses are the same temps. I decided to takle the blend door and sure enough the actuator peice was broken. I did the heater treater fix and now it works fine. I can even rotate the blend door with my fingers when it's apart. But I still have no heat. I do have the vacuum leak somewhere with only my defrosters working if that matters at all, I have vacuum all the way up to my switch and replaced it with a new switch and that still doesn't work so I gave up there

 

How hot are the heater hoses? New thermostats don't always work. In the DIY section there is a thread on burping the coolant system.

 

When you move the blend door from one extreme to the other, do you actually hear the door thump against its stops? There have been occasions when the door actually separates from the axle.

 

The hoses are really hot. I can confirm the thermostat works by watching the temp gauge. As far as hearing it on the stops I do not. When I turn the dial from one extreme to the other I can get in the floor board and watch it spin but it doesn't seem to be going fast enough to hear a thud. It spins VERY slowly. Now if I take it apart and spin it left and right with my fingers faster I can hear the thud on the stops.

Also I don't know if this helps. If I leave the heater off and then turn it on. It's hot for like 5 seconds and cools off

 

Might just be time for a new core. After all, it's 18 years old. I had what you had a few years back but the heatertreater fixed it. And my core is shot now too.

 

I would suspect restricted flow thru the core, or an air pocket.......

 

Yeah it's got me stumped for the most part. I've burped the system several times and like I said when I flushed the core it had great flow and the hose coming out of it will toast your hand so I know there is really hot water going through the core.

So how would I go about checking to see if the door has separated from the axle?

 

Aside from taking it apart, and looking.... not sure. I don't think there is a really good angle you can get to see it while it is assembled. maybe a bore scope?

 

You've already done the heatertreater. Time to pop the motor off again.