No heat after freeze plug replacement

[sam3]

Title says it,
-power to the heater control, power to the heater valve, heater core is not blocked, replaced the heater valve and can feel the solenoid working when the knob is turned. tried a new switch with same result.
The lower heater pipe gets hot to the valve but no further. System seems to be bled out but I'm wondering if the core might be air-locked and, if so, how to fix it.
Car maintains perfect temp with no leaks.

One caveat, the car was parked all summer and it's not known when the heat quit, guessing it's probably related to the coolant service though.
Thanks

[jlevie]

The heater could be full or air.


1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.