HVAC Issues! No Airflow From Front Vents

[bspillman]

2017 Ford Expedition EL Limited - Sync 3

Having an issue with my front vents today. After 15-20 min of driving the air stops blowing. I can hear the blower motor running, but no air is coming out of any of the vents. Sounds like there is a door closed blocking air flow. If I shut the truck off, let it sit for a few minutes and then turn the truck back on, the air starts blowing out of the vents just fine. The air will blow for another 15-20 min and then the airflow will stop again.

I have replaced the actuator to the right of the gas pedal with a new OEM part. That didn’t fix the issue.

The blower motor and resistor were replaced under the recall a year ago and I have verified it is operating on all speed settings.

Rear A/C, Heat and Blower work as normal.

Anyone else have this issue before?

 

[Dennis_H]

Seems weird that the blend door would close, they usually just get stuck in one position.
Could be low on refrigerant and evap is icing up and not allowing air through it. When you stop, it melts enough to let air through. It's hotter in the back and maybe it isn't icing there? Just a thought.

 

[GaryH]

Vacuum leak perhaps? The doors are operated by engine vacuum. When there isn't any vacuum, the doors close. I think.

 

[bspillman]

Seems weird that the blend door would close, they usually just get stuck in one position.
Could be low on refrigerant and evap is icing up and not allowing air through it. When you stop, it melts enough to let air through. It's hotter in the back and maybe it isn't icing there? Just a thought.

I thought it was weird too. Its definitely something to do with the blend doors. I only have to let it sit for 2-3 minutes for it to start working again. I wouldn't think that would be enough time for ice to melt. It does the same thing on heat too. It was cold this morning so I had the heat on driving into work. Sure enough, after 15 minutes, no air flow.

 

[bspillman]

Vacuum leak perhaps? The doors are operated by engine vacuum. When there isn't any vacuum, the doors close. I think.

Not sure how the older Expeditions operate, but the doors on mine are actuated by electronic motors.

 

[GaryH]

Not sure how the older Expeditions operate, but the doors on mine are actuated by electronic motors.

Hmm, didn't know that. Well maybe there is a relay that's overheating or malfunctioning. Just offering ideas.

 

[bspillman]

I used an Autel scan tool to clear the codes in the HVAC module and I haven't had the issue since. I'm guessing the old mode door actuator set a code and because I didn't clear them after I replaced it that was causing my issue? Don't know, but I was able to drive into work and back home (over an hour each way) without any issues yesterday.

 

[catsailr]

I had that happen once and a plastic bag had been sucked into the air intake under the dash.

 

[Ellison Brown III]

Vacuum leak perhaps? The doors are operated by engine vacuum. When there isn't any vacuum, the doors close. I think.

Not sure how the older Expeditions operate, but the doors on mine are actuated by electronic motors.

That the is correct, the blend (hot and cold) and mode (feet, face, or defrost) doors are electronically actuated.

On the older models (thinking about my ‘04) the only thing that comes to mind in the HVAC system that’s vacuum actuated is the heater control valve that’s under the hood near the firewall on the passenger side. It controls heat; or, the amount of antifreeze allowed into the heater core for heating purposes.