EATC and BCM are fine yet air only blows out vents

[DeadVic]

I've read all the threads related to both EATC and BCM. I have a 05 Sport and an 03 MM.

The 05 sport is having the issues. I swapped out the EATC and problem on Sport persists.

I can hear the blend door moving when moving from floor to vents to defrost. AC works, Max AC works as it should, getting hot air when set to appropriate temps, airflow control is as it should be in each location. EATC diagnostics comes back clean. But the air flow when set to floor or defrost is coming out the vents. I am getting a mix of floor and vent on heat. and a mix of defrost and vent when on defrost. something isn't fully sealing when the blend door moves or something along those lines.

Can someone help me narrow this further? Thanks!

[fastblackmerc]

I've read all the threads related to both EATC and BCM. I have a 05 Sport and an 03 MM.

The 05 sport is having the issues. I swapped out the EATC and problem on Sport persists.

I can hear the blend door moving when moving from floor to vents to defrost. AC works, Max AC works as it should, getting hot air when set to appropriate temps, airflow control is as it should be in each location. EATC diagnostics comes back clean. But the air flow when set to floor or defrost is coming out the vents. I am getting a mix of floor and vent on heat. and a mix of defrost and vent when on defrost. something isn't fully sealing when the blend door moves or something along those lines.

Can someone help me narrow this further? Thanks!

You said you read all the posts, did you replace the o-rings?

Have you checked for any loose hoses or vacuum leaks?

[FordNut]

Sounds like the EATC is controlling vents like it should but the air temperature isn't being controlled properly. Maybe the blend door actuator.

[DeadVic]

Yes, I did change the o rings first. it didn't work. so I then swapped a known working EATC (out of my MM) into the Sport. Sport continues to have same issue with working EATC.

I have not tested for other vacuum leaks

[FordNut]

I guess other vacuum leaks are a possibility, check out on the firewall where the vacuum manifold connects to the intake manifold. I got kind of confused by this:

"airflow control is as it should be in each location..... But the air flow when set to floor or defrost is coming out the vents."

[DeadVic]

Sorry about the confusion. I should have said "AirTEMP control is as it should be in each location. The air flow when set to floor or defrost is coming out the vents".

I retraced my steps, lubed the orings a bit (did them dry last time) and no change.

I run the car, run the HVAC, shut the car off and then I can hear a hissing air "leak" under the hood. coming from the area around the intake. Is this normal upon shutting the car off? I don't think it is but am unsure.

Thanks for your help. I appreciate it.

[RF Overlord]

I'll take a stab at it...

The square plastic black box on top of the driver's wheelwell is the vacuum reservoir. If you're hearing hissing from that area, check to be sure it isn't damaged or the hose is cracked. There's also a check valve in the line coming from the intake manifold, but I'm not sure where that's located.

If your temperature can be regulated properly, but the direction of the air is wrong, the the blend door is fine; it's the "floor/defrost" door and/or the "panel" door vacuum motors and circuits you should be looking at. Those are labelled as vacuum circuits 2, 3, and 4 from the EATC.