Blender door or other issue possible? No heat.

been reading all i can scrounge up. found one similar thread, with no resolution. car blows room temp air all the way on hot. if i quickly crank it from coldest to hottest, i get a surge of warmer air. then it quickly (1-2 seconds) settles back to room temp.

one other thing i noticed, my dial doesn't "stop" evenly on cold/hot side. my cold side, if you turn it to max cold setting, will rebound back almost half way up the cold range. my hot side, will turn all the way down and settle there.

it leads me to believe its the blender door? is this linkage accessible with the dash in place? i dont recall. is there any good info on how to adjust this linkage specifically? if its NOT sounding like a blender door, what else could it be?

new heater core
both hoses get hot
all vents work
13-15 hg at idle via autometer gauge. 950 rpm idle with tfs stage 1.
thermostat is new and opens at correct temp
no leaking coolant
full radiator

ill take a look at it and spray it with some wd.

it seems almost like the cold movement is maxed out when its at 9 o'clock position if it were a clock. when you turn it down to 7 o'clock at the coldest setting, it just rebounds back.

i've never looked at the linkage. hopefully its visible without tearing half the car apart.

i put some wd40 on the cable and nothing changed. i did find some other info though.

i have an autometer gauge on the front corner of the intake. i moved the stock sending unit to the back of the intake. my drive to work is like 8 miles. the car was at full temp for like 6 miles. my stock temp gauge didn't move, while the car was at 175* on the autometer.

it takes forever for the stock gauge to move, when it gets up to operating temp, it sits at 180ish on the stock cluster. i got to work, and let it sit there for a minute idling. the stock gauge moved a tiny bit, and the air got a little warmer.

so the air i get from the vents, goes according to my stock temp gauge. how does this make any sense when prior to the stock gauge getting warmer, my heater core hoses are already hot?