I have a 2007 Ford E250 cargo van when accelerating the diverter closes the damper on the air-conditioning and it will cool again after acceleration is over. I know it's some kind of vacuum issueWhat the fix for this problem?
07 should have electrical servos for blend doors and mode doors not vacuum. Can you actually hear the blower speed change when this happens due to mode change? What I think is happening is the WOT switch is activating during acceleration, it turns off the A/C compressor during acceleration or climbing a grade, it turns it back on again when speed is normalized or grade level is achieved.
I'm not sure that the compressor is actually turning off. Air flow through the vents drops completely during aggressive acceleration/incline. However when there is mild acceleration/incline, I can feel air flow backing off slightly. I also noticed when the air stops coming through main vents that it diverts for a split second to the defrost vents because a piece of paper on the dash blows up during the transition. Another reason I think the compressor continues to run is when air flow returns to the main vent it hasn't lost it's chill whatsoever. I'm assuming if the compressor turned off and back on again, it would have to build back up before peeking. I'm pretty technical minded, as repair appliances for a living. However I don't have a complete understanding as to how this system works.
OK do the controls have any digital read outs? If not then the system is manual, and there will be vacuum lines and motors, this type of problem is usually caused by a leak in the valve behind the control head, the problem is that you almost have to completely remove the dash to gain access to all of the control motors, but you might get lucky and it be just the control valve, if you don't have enough time to tear it down you can put in an auxiliary vacuum tank on the heater main vacuum supply hose, you can find a lot of them at your local auto recycler. A vacuum chart would help you with this, check with your parts store to see if they have or can get you one, it might be included with a manual. HTH
The AC/Heater register controls are vacuum actuated. There is a vacuum line that runs down the right side of your intake manifold to a vacuum "T", a vacuum check valve and a plastic vacuum canister. The check valve and the canister supply vacuum to the register controls whenever there is a low vacuum condition (such as moderate to heavy acceleration). Typically, the check valve has failed. It looks like a small "F" with a round, flat check valve.
#'s 13, 14 and 15
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