Possible A/C Blend Door Issue

calabrz · Nov 19, 2021

2006 Expedition Limited

I am having an issue with my a/c. While driving the a/c will blow cold from the front vents on and off. I have found that when I am driving up hill the front vents will stop blowing, but as soon as I start going downhill the air starts blowing through the front vents again. This also happens when the air starts off on high as soon as I put it to low they air starts flowing through the front vents again. I can also get the air going when I brake. I was told this could be a blend door issue. Any suggestions on how to fix this? I was quoted $1,000 because the dash needs to be removed.

Thanks in advance

Hamfisted · Nov 20, 2021

Sounds more like a vacuum leak. Inspect the vacuum lines under the hood for leaks, cracks, soft rubber. Pay particular attention to the small lines behind the battery and the supply line running through the firewall grommet. Of the two lines passing through the grommet, the bare line is the supply line, the other one with the shroud over it is the vacuum control line to the hot water valve in your heater hose. Any leaks in those lines, or a bad check valve, will cause a loss of vacuum to the dash vent control solenoid and your vent doors will fall to the default defrost position.

Dash vent system vacuum control solenoid ( located under dash at front of center console ....)

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calabrz · Nov 20, 2021

Thank you for the reply and photos. I checked under the hood and discovered the vacuum control line to the hot water valve is disconnected nor do I know how it became disconnected. Is this an "easy fix?' Can I get to the solenoid without removing the console or dash?

Hamfisted · Nov 20, 2021

It's easy for that line to come off. Especially when changing sparkplugs or anything in that area. Just reconnect the line to the hot water valve and that'll probably fix your problem. Unless there's other lines that are broken or leaking. But having the line off the hot water valve is enough to do what you described earlier.

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calabrz · Nov 21, 2021

Well... the line is connected to the water value and disconnected from I guess the solenoid. Does this end go through the firewall, if so where and is that an easy DIY?

Hamfisted · Nov 21, 2021

Yes, see the first picture I posted above.

calabrz · Nov 21, 2021

Last question... I hope.

Does the line simply fit into the hole and into the solenoid or do I need to go under the dash? If under the dash, do I need to remove the dash or console?

Hamfisted · Nov 21, 2021

Some folks have had luck just sticking that line back into it's hole in the firewall grommet. Take a bright flashlight and see if it looks like a clean tiny hole to stick that tube into, or if there's a piece of tubing still stuck in the hole you might need to pull out. Depends on if the tube was broken or just yanked out. The tube seems to get damaged when people replace the battery and set the battery down in the tray without clearing all the tubing out of the way first.

Vincent Vega · Dec 28, 2021

Hamfisted said:
Some folks have had luck just sticking that line back into it's hole in the firewall grommet. Take a bright flashlight and see if it looks like a clean tiny hole to stick that tube into, or if there's a piece of tubing still stuck in the hole you might need to pull out. Depends on if the tube was broken or just yanked out. The tube seems to get damaged when people replace the battery and set the battery down in the tray without clearing all the tubing out of the way first.

@Hamfisted the good news is I replaced the timing set on my '04. The bad news is that, as I was removing the RH valve cover, I accidentally pulled out the vacuum supply line that goes through the firewall as shown in your photos above. The blend door setting is stuck on Defrost. The hot water valve line is ok and in place.
Do I need to remove the dash to plug the line back in? The only other possibility is maybe if I rip out the grommet in the firewall, I might be able to see through enough to where it plugs in. I know that is not ideal. Thanks.

Hamfisted · Dec 28, 2021

Yeah pull the grommet out and see what's left there. Or maybe you can fish the line out to reconnect the two.

Possible A/C Blend Door Issue

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