When flushing the heater core be sure you flush it in both directions. Flushing in one direction won't get everything.
I just flushed mine out this weekend after having really poor heat this winter. After connecting my hose to the heater core inlet and flushing until clear water came out, I put the hose on the outlet and back flushed the heater core. More antifreeze came out and so did a lot more gunk.
You need to be careful with the amount of water pressure you use if you know your heater core is leaking. I'm pretty sure I read that the amount of water going through the heat system is 18psi. Too much water pressure may do more damage.
I just flushed my heater core, put in new 195 thermostat and flushed the whole system (radiator,block) n I have heat now. Not cooking any roasts on it but definately ALOT warmer than it was. C how it does when it gets cold again
The door should have cable it's on the box bottom side of the passenger side , you wanna make sure the lever is all the way forward for heat as long as you hold the clip in pace and push the lever it should readjust it self when you move the lever .