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Air only blows out floor and defrost vents

As stated in the title, I am only getting air blowing out of the defrost and floor vents but not the ones in the dash. I have installed a new blend door actuator (at the passenger side) and realized after the fact that wouldn’t have helped my issue.

My question is this: which part controls the vents in which the air flows? I know there is often a faulty check valve on the vacuum line but are there other issues that can cause the failure that I’m experiencing? In all honesty, I’m not looking to pull the dash/heater core/etc if I can avoid doing so but if need be, that’s what I’ll do.

Thank you in advanced for any and all help!

There’s a problem with the mode door(s) or the actuator(s)


With the engine running at operating temperature check the 2 hoses that run from the engine to the firewall. Both should be hot. Are they?

It’s called the “mode door actuator”

What year model is the truck? Because when Ford put the “mode door actuator” on their vehicles it was notorious for failing for several model years and it was a real pain to get to. I’m amazed that @Tester 's post didn’t ring a bell on my memory.

Defrost and heat vents is the default when the system fails. Start with the vacuum line and check valve. You might get lucky.

It’s a 2013 E150 base model, V8 4.6L.

After a few hours of initial research, I did read that it is likely the mode door actuator and I still suspect that to be the issue but I have not been able to find any solid information as to where it is located. As I said before, I did replace the blend door actuator but realized afterward that doing so was pointless as the temperature selection knob has been working well (hot air when selected, cold air when selected, and AC when selected).

I decided to purchase the Haymes repair manual hoping it would have information on the different actuators and their respective locations, or even a diagram detailing where the handful of tiny vacuum hoses used for the climate control run to and from/what each color hose controls, but no luck there. I also spent hours searching online for similar information but haven’t been able to find anything there either.

That being said, is there any online resource that I could use to find what I’m looking for (specifically a vacuum hose diagram and related information)? If not, do you know where the mode door actuator is located? My guess is that its behind or under the dash and if I need to remove it I will but I’d prefer to keep the disassembly to a minimum. Lastly, even when I’ve searched for “mode door actuator” and similar terms on different auto parts websites, I’ve only come up with the blend door actuator (which I’ve already replaced) so I don’t even know what the mode door actuator looks like, making my attempt at searching for it come up empty.

Thank you again for any help you can provide and please be safe out there with all this COVID-19 stuff hitting the fan.

I suspect it is the mode door actuator but I have no idea where that part may be located in the van. Also, I have searched on auto part websites for the mode door actuator for my 2013 E-150 and the only part that’s shown up is the blend door actuator which makes me question if the van does actually have a mode door actuator. Also, amongst hours upon hours of online research, I cannot find any information regarding the mode door actuator, the location of it, or a diagram of the vacuum hoses that have to do with the climate control for the vehicle.

Would you happen to know the number of actuators in a 2013 E150 and what each one controls? I know the blend door actuator that is located behind the glove box controls the temperature of the air flowing to the vents but are there other actuators (outside of the mode door)? Is there another term for “mode door actuator” that Ford may use for the part? Lastly, where would the mode door actuator be located in the van (driver side dash, passenger side dash, etc)?

Thank you for your help

Both hoses are hot. Where do the hoses lead to/what do they do? Do they circulate coolant to the heater core? As a side note, I am not having any issues with temperature control and I recently replaced the blend door actuator. Also, the heater core is working properly and shows no signs of failure/steaming/leaking.

I suspect it may be a check valve issue but from what I’ve seen online, getting to it would likely require the removal of the blower motor, heater core, draining the coolant and possibly the refrigerant as well. I’d really like to avoid having to do that and possibly end up finding out that the vacuum hose and check valve are in working order. I may have to do that eventually but I’d like to explore less involved options first and narrow it down from there…

Because I’ve had this issue for a while now and only recently decided to tackle it as summer is coming, I forgot to mention one other symptom that was occurring before the dash vents stopped blowing air: When I would accelerate while using the AC, the air flowing from the dash vents would drop drastically until I let off the gas pedal. I don’t know if it was also happening when blowing heat from the vents though as it was summer time when I noticed the drop in air flow.

Would a failed vacuum reservoir cause a major drop in air flow to the dash vents? I’d think so but would that also cause air to barely blow out of the same vents when not using AC and/or heat?

Thanks again!

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Classic signs of a vacuum leak in the HVAC system controls, assuming your system is vacuum controlled (you haven’t told us the year of your van). Start by pulling a vacuum on the line to the HVAC and see if it holds.

Look above the brake/gas pedals to see if it’s located there.


There is a vacuum check valve somewhere in the hoses leading to the HVAC control unit. It is usually between the engine intake and the vacuum reservoir.

this is a common check valve but there are others. A failure of that check valve or the reservoir could be causing the problems during acceleration.