My heater doesn't heat. Cold ambient temp air. Not AC air when in heat mode.
I replaced all three switches. No effect.
I checked vacuum operated control valve under hood for fluid flow. No effect.
I blew out heater core with air. Clean. No effect.
I checked doughnut shaped moveable door near passanger door. It works.
I check the other actuator near accelerator pedal. The actuator moves.
It blows cold ambient air
It shifts air flow to appropriate locations when far right switch is activated.
When far right switch is moved to the airflow position for upper and lower air flow, the AC compressor periodically goes off an on.
AC works correctly when in AC mode.
When far right switch is moved to floor airflow only, no AC compressor movement.
All other switch positions on all three switches seem operable as designed.
The hoses to and from the heater core, under the hood, are both hot.
The vacuum operated switch under the hood operates as designed: Active on AC and no vacuum when AC off. Plunger moves with vacuum active.
I took off the hose from the vacuum operated switch under the hood and started then engine. Water came out of the port closest to the radiator. All the hoses to and from that switch were hot.

Peculiarities: When in heat mode for bi-level airflow and floor only airflow, the vents at the hood and windshield interface are sucking air. I never noticed this before which may be what it does and I never noticed it.

My thoughts: There is some other electrical "box" on top of the heater core container behind the glove box which may be mixing air inappropriately. The electric box has wires plugged into it, is cream colored, bolted to the core box under the dash/glove box. But, I have not idea what the problem could be: just guessing.

Any knowledge you could share will be appreciated. It will be cold again soon.

TIA
Josephus

 

I just found GRRR's post and I think I need to revisit my heater core flow.

So, let me do that before anyone spends any time on my post.

I did not see his post until a few minutes ago.

TIA,

Josephus