here we go again...A/C ventilation problems
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Junior User
Joined: Dec 2004
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here we go again...A/C ventilation problems
I just replaced both rear actuators, and not even a month later now the front AC ventilation is only blowing out of the windshield defrost mode, regardless of what mode I put the ventilation to....
I reached under and I can see the actuators for floor and dash ventialtion and by manually moving them I can get the air to flow thru the dash and floor....so have they both gone bad??? this sucks
I reached under and I can see the actuators for floor and dash ventialtion and by manually moving them I can get the air to flow thru the dash and floor....so have they both gone bad??? this sucks
Logistics Pro
Joined: Jul 2003
Posts: 3,595
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From: Lawton, Oklahoma
The rear actuators are electronic and the front ones are vacuum. You likely have a vacuum leak. Check all the vacuum lines especially under the hood for broken or chewed through by a rodent.
Logistics Pro
Joined: Jul 2003
Posts: 3,595
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From: Lawton, Oklahoma
The only thing that has wiring going to them would be blend door actuators which do not control the air flow direction. The vacuum actuators control the door positions. How would you manually push an electronic actuator with a motor driven shaft? The late model F150 has electronic motors on all the doors but I havent seen that on Expeditions.
Last edited by HomerWinzlow; Dec 16, 2006 at 04:25 PM.
Laughing Gas
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Originally Posted by HomerWinzlow
The rear actuators are electronic and the front ones are vacuum. You likely have a vacuum leak. Check all the vacuum lines especially under the hood for broken or chewed through by a rodent.
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HomerWinzlow, you were right man. Those wires I was looking at were actually vacuum lines after I got in there a little closer, they are just colored coded like electric cabling.
Anyways, I cant find a leak anywhere and is still little warm here in FL, so I forced the actuator open for the front vent and tie wrapped it in the open position so air blows out the front only....oh well, not really how I like to do things but hopefully I will run into the leak one day
Anyways, I cant find a leak anywhere and is still little warm here in FL, so I forced the actuator open for the front vent and tie wrapped it in the open position so air blows out the front only....oh well, not really how I like to do things but hopefully I will run into the leak one day
New User
Joined: Jul 2005
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I have a 98 Expedition with the same problem. Only the defroster vents have air flow. However, they do blow hot and cold when the A/C and heater are used. I suspected vacuum lines, but I don't see where the main vacuum line feeds into the cab from the engine compartment. The failure mode was rather odd. One night the airflow control worked, and the next morning it didn't. On the night it worked, I drove through some deep water in one of Phoenix's notorious heavy rainfalls. I suspected that maybe the water flow knocked a vacuum line loose somewhere low. The engine doesn't exhibit any signs of a vacuum leak, though. I checked the vacuum actuator with a hand vacuum pump, and it works fine. Does anyone have a suggestion on where to find that master vacuum feed to the airflow control system at its origin inside the engine compartment? Is it a black line? Does the main line feed directly into the flow control switch, and then the flow control switch ports vacuum to the respective actuators? Thanks in advance for the help.
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Logistics Pro
Joined: Jul 2003
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From: Lawton, Oklahoma
If you have inspected all the lines under the hood visible you need to look behind the battery at the vacuum reservoir tank, the lines leading to it and under the fender inner plastic protective panel between it and the fender are plastic lines on some as well as a second reservoir on some 4x4 vehicles.
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The plastic vacuum line located between the battery and the firewall is, by far, the most common failure. There are other spots that fail, but this one is easy to check and repair if needed.
Steve
Steve
New User
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Eureka...now what?
Thanks all for the good advice where to look for damaged vacuum lines. The good news is that I found the damaged vacuum lines. The bad news is that these vacuum lines look difficult to repair. I located what appears to be a series of 4 lines that connect at a connector junction. One line, a black one, appears larger than the others which all appear to be white; all the lines are a hard plastic tubing. It appears that at least two of the lines on top of the 4-tube connector, a large black one and a small white one have melted, perhaps due to acidic battery fumes. I am guessing this failure mode, becuase the vacuum lines are located right next to the bottom of the battery box, between the battery and the firewall. Does Ford make a splice kit to repair these lines? If not, can I splice them with traditional vacuum lines? How have you all tackled this repair? Many thanks for the help!
New User
Joined: Jul 2005
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Success at Last!
Well, thanks to the fine people working this thread, I have succeeded in restoring normal operation to my air flow control system. The problem was three vacuum lines between the battery and firewall. There is a 4-way connector with one 1/4" line and three 3/16" lines. One of the ports is not used on this connector. All three lines were broken, but it was not possible to observe this via a casual inspection. They were cracked, but not separated at the crack. It was fairly easy to fix the lines. Remove the battery, then all the lines are easy to get at. Remove the short broken ends from the rubber connector, trim the remaining good line, and insert the trimmed end back into the connector, where the line was previously connected. It cost about $10 for parts at Autozone. Good luck to all who are still fighting with this problem. I hope this easy and inexpensive fix works for you.
