08 Explorer air blows from defrost and floor on floor setting

[relentless85]

I recently replaced the heat and air controls and the vacuum lines that go from the controls, down to the black resivour then goes through the firewall.

When I turn the knob to make the heat/air just come out of the floor vents, some air comes out of the floor and more air comes out of the defrost vents.

When the knob is turned to dash and floor, air comes out of the dash, defrost and some very little out of the floor.

I don’t know what else to replace to make the air just go to the floor when the knob is set to just the floor setting. I don’t hear any vacuum leaks in the engine compartment or the black resivour under the dash. I made sure all the connectors on the lines I replaced are clean and tight. The new vacuum lines came with a new check valve for the vacuum line that goes up by the intake manifold.

Any ideas? Is there a motor I’m not thinking about that might need to be replaced that controls e position where the air blows from? Is there something else that needs to be replaced in the engine compartment?

 

[Larryjb]

There is a check valve in the engine bay by the firewall. I forget the exact location, but you should be able to find it if you know what you are looking for. This check valve may need replacing as a faulty valve can cause your symptoms.

 

[relentless85]

I know the check valve you speak of. A new check valve came with the new vacuum line assembly kit. I also made sure the check valve was the correct way and connections are tight.

There is a “main” vacuum line assy that goes from the front driver side area of the intake manifold that leads into the check valve. But that “main” line looks to be in good shape.

There also is some sort of valve? That a vacuum line goes into on the passenger front. Looks like the valve has to do with the heater lines as it looks like it has coolant lines running through it.

So I don’t know what else to replace/test/look for. The main vac line on the intake manifold, the valve that the coolant lines go through or some other motor inside the dash that I’m not thinking about??

 

[94Eddie]

I just replaced the check valve due to the reservoir losing vacuum due to it leaking. I got mine from Amazon.

https://www.amazon.com/gp/product/B000NU8FFY/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

 

[michael loibl]

A small amount of air (maybe 20%) is supposed to go to defroster even when set to floor, but it sounds like you are saying the majority is going there. Does the amount change under various driving conditions such as low RPM high load?