I have an 03 expedition with 46K miles. I noticed my heat is not working right now that it is cold. This is especially true when the vehicle is not up to full operating temperature yet. What happens is that when I have the defrost/floor or front vent/floor selected (front) with either the max fan or next to max and I get nothing coming out at all. This sometimes happens with just defrost as well. The fan is obviously heard but no air coming out. If I then turn the temp to cold the air starts coming out. Is this a common problem? What exactly is going on? Ideas where to look, what might be broken, etc? Is the expy hvac system the same as say an 04 f150?

 

Bad blend door motor behind dash. I believe it is behind where the center console would bolt. Not sure. The motor is stuck in the cold position.

 

Also could be a vacuum leak, Check vacuum lines under hood first. I did my cops and forgot to reconnect a vacuum hose... was pissed till ii found I forgot to reattach a vacuum hose (also gave me a check engine light and backed into my mistake)

 

I don't get a check engine light at all. I am thinking it is not the blend door issue because wouldn't the blend door problem be the same whether or not it is cold vent or heat? The problem only exists with heat and it is when a dual heating mode is selected like floor/defrost or front vent/floor. Where are the vaccuum lines that I shoudl be checking for this?

 

I don't think it is either of the above ideas.

Sounds to me like the airflow through the heater core is restricted since, if I interpret your description accurately, you get normal airflow from any selected outlet when the temperature selector is in COLD but you do not have outlet airflow when the the selector is in HOT. The only thing that would explain that behavior is that air can't flow through the heater core.

Vacuum faults will manifest as a loss of control of air outlet and inlet.

A malfunctioning blend door or actuator will show up as a loss of control of outlet air temperature but will NOT affect outlet airflow volume or destination.

Do try to confirm that you're loosing airflow from ANY outlet (and it's not just going elsewhere) when the fault occurs.

Steve

 

I have full outlet airflow when the selector is in HOT with ONE destination only. If I split it like defrost/floor then I get virtually nothing. It is not going out somewhere else. The fan speed is as it should be and I can hear it just not coming through anything.
Also, this seems to have gotten a bit worse as sometimes I used to get it working with both destinations after the vehicle was running a while but now not at all. It is one destination or nothing really.
I don't see how it could possibly be a heater core issue when it works just fine with one outlet. Air is hot and flow is good.

 

Maybe the little air flow door motor is dead? It seems to happen a lot to the rear air flow door in the 03 Expys. Usually, one of the gears looses some teeth, and a clunking noise is heard. The air only comes from the vents when in hot?

 

Works in ALL positions when COLD. Only works with ONE destination when HOT. This is a problem with the front only. Not the rear.

 

Dirtrider

Did you ever resolve this problem? I have simular problem with 1998 Expy with front & rear HVAC. All vent positions were receiving normal airfolw with Control **** in hot or cold positions. Air would start out warm when set to hot but then turned cold. AC worked fime in all postions front and back.

I still have the no heat problem but just recently the airflow in all selections and positions blow out the defrost vent.

 

No I never got a resolution and never took it to a dealer to diagnose. I have just lived with it. No check engine light or anything.

Really mysterious to me and none of the above posts seemed to have a good possibility/resolution. Now I never seem to get full flow through the front defrost port no matter what if the temp is set to hot. Flows fine for cold though. Only way that hot seems to work at full speed of air through an outlet is if it is blowing straight out the front of the dash. Fan is clearly heard operating at full speed and temp is hot so I don't think it is the heater core (and I have since flushed the coolant). It must be vacuum or blend door then right?

Would be nice if someone had any other ideas for me. I read the older versions of the expy had the blend door problems but 2003 was the redesign and I haven't seen posts of problems with that year model. Perhaps it is a vacuum issue but I don't know where to look.

 

Do you have a manual AC (with *****) or the electronic one?

 

Manual. ***** have been switched around to see if broken and they are not. Selections for air output location feel just as they always did...no problem with the manual selector that I can tell.

 

I'd be suspecting that a critter made a nest in the plenum (or something similar)...

 

Can you list all the combinations where the heat will not work? Panel/Defrost and what else? And this is only on speeds 3 and 4?

 

Sorry I missed this somehow. Anyway, the worst combination is defrost/floor. On speeds 3 and 4 no more air comes out than 2. However the fan is obviously heard loudly so I know it is at the proper speed. I'm not sure where that extra air is redirected but it is not coming out the vents. It seems like other combos offer lesser air flow than when new too and sometimes even just defrost only doesn't even hardly flow at all at speed 4. Sometimes it works decently but I don't think it even flows like when new.