Not a real technical question, but...
2002 F350 drw 4x4 PS Centurion. Blows air out the defroster vents ONLY.
Blows hot when turned to hot, blows cold when the AC is on, but only out the defrost vents.
No dash , no floor.
Any common things to look for?
Hopefully i wont have to tear the whole dash apart like with the wife's Durango....... O,o
Thanks for any input or links......

any links to schematics on dash, heater control/core?

 

You are a describing a common symptom of a vacuum leak. You 4x4 hubs are controlled by vacuum as well as which vent your hot/cold air flows out of. More than likely it's a leak in your 4x4 hubs esof system(electronic shift on the fly) I would search this forum or YouTube for information on diagnosing your problem.

 

X2 with Jason, most common issue would be rotted rubber hoses that operate the ESOF 4X4 hubs. The hoses run from a clip on the frame to the front hubs, and they disintegrate with age. Then you have a massive vacuum leak and the HVAC control defaults to defrost. Check this link for some pics and diagrams first, then check your hoses.

Edit: and welcome to FTE!

 

The ESOF is activated by the PVH (Pulse Vacuum Hub) Solenoid and operates only when engaged by the Dash Switch for 4x4 via a 12 VDC Signal.

The PVH has two nipples, one below the other (stacked) The Top is for the Cab, Bottom for the ESOF, the Diaphragm is on the bottom.

1. Ensure your vacuum pump is working and stops following 20 - 30 seconds of operation indicating a 15 hg in the Vacuum Canister. If it doesn't stop, check the vacuum line attachments at the PVH.

2. Ensure the Vacuum Container is not leaking.

3. There are 2 lines connected to the PVH, the Red one supplies vacuum to the Head Unit in the Dash. There is a quick disconnect between the PVH and Firewall on the passengers side. Disconnect it, use a vacuum pump (with a helper) and maintain 10-15 Hg on the Gauge.

4. Use the selector to change the mixing door locations (Vent, Floor, Defrost, etc.).

5. If you can not maintain vacuum, the issue is between the Hand Pump and the Head Unit, if this works, the issue is either a faulty PVH (Which wound engage but not disengage the Hubs) Vacuum Line deterioration or Vacuum Boost Canister.

To check the ESOF Side of the PVH:

1. Connect a vacuum gauge to the lower nipple (black line) and engaged the 4x4 after the Vacuum Pump stops indicating the canister has 15 Hg.

2. You should witness a 15 Second Pulse of 15hg (required to engage the hubs)

3. Disengage the 4x4 and you should witness a 6 second Pulse of 10 Hg (required to disengage the Hubs).

When a loss in vacuum occurs, the mixing door defaults to the defrost to ensure the windshield can be de-fogged in inclement weather.

 

It's covered above - vacuum leak (assuming you hear the vacuum pump running).

 

Wellllllll, didnt have a vaccume guage or testers, but tryed pulling lines and testing "seat of the pants way.
Pulled the hose above the red hose on the solenoid (felt "funny") and it cracked. spliced it w some old junk rubber v hose, plugged it in and tried it.
Seems to work normally.....so far.....((((knock wood))))
Thank y'all for the schematics and info!
It helped immensley!
Have a great day! ;-)