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Thread: a/c zones switching randomly

  1. #1
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    a/c zones switching randomly

    Hello, I searched the Shop Talk, and couldn't find an answer so certain y'all can help. Recently, my a/c will randomly switch zones (if I have it on normal or max) when I initially start up (it'll go through the floor, defrost, vents) then about 5-10 mins later "level out" and blow through the vents as it should. Super frustrating. Any advice?

  2. #2
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    It is most likely your EATC module. That is the module in the dash that you use to set your air and heat with. There are rubber grommets inside that get old and do not seal so it causes your changes in settings. Search under EATC repair and you will find information about how to repair it. Or you can PM Fastblackmerc and he will fix it for you for a modest fee.
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  3. #3
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    I like your screen name.....

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  4. #4
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    Quote Originally Posted by ammolance View Post
    Hello, I searched the Shop Talk, and couldn't find an answer so certain y'all can help. Recently, my a/c will randomly switch zones (if I have it on normal or max) when I initially start up (it'll go through the floor, defrost, vents) then about 5-10 mins later "level out" and blow through the vents as it should. Super frustrating. Any advice?
    Most likely it's your EATC o-rings. I can repair it for you and upgrade the button & fan wheel lights to LEDs.
    “When you can’t make them see the light, make them feel the heat.”
    Ronald Regan

    "The only way to deal with the Islamic State - these blood thirsty, blood-drunken, terrorists -
    is to kill them, keep on killing them, until you kill the last one, then you kill his pet goat."

    Lt. Colonel Ralph Peters

    “Be polite, be professional, but have a plan to kill everybody you meet.”
    "I come in peace. I didn't bring artillery. But I'm pleading with you, with tears in my eyes, if you **** with me, I'll kill you all"
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  5. #5
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    Arrow

    Quote Originally Posted by ammolance View Post
    Hello, I searched the Shop Talk, and couldn't find an answer so certain y'all can help. Recently, my a/c will randomly switch zones (if I have it on normal or max) when I initially start up (it'll go through the floor, defrost, vents) then about 5-10 mins later "level out" and blow through the vents as it should. Super frustrating. Any advice?
    What are the outside temps and what temp is the unit set at when it does this? Is this new behavior? Are you new to the car?

    I'm new to the Marauder, having bought mine in late March. I've noticed that if I start my unit when outside temp is in the mid 60s or lower (first thing in the morning) and the unit is set to the mid 70s for higher it will automatically start in the defrost mode. The unit will switch to the dash vents once the outside temp rises and/or I lower the internal setting. If I remember correctly, both my '71 and '79 Cadillacs with the Climate Control did the exact same thing.
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  6. #6
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    Quote Originally Posted by fastblackmerc View Post
    Most likely it's your EATC o-rings. I can repair it for you and upgrade the button & fan wheel lights to LEDs.

    That'd be awesome, but I'm down in the panhandle of FL now (Panama City).

  7. #7
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    Quote Originally Posted by Invective View Post
    What are the outside temps and what temp is the unit set at when it does this? Is this new behavior? Are you new to the car?

    I'm new to the Marauder, having bought mine in late March. I've noticed that if I start my unit when outside temp is in the mid 60s or lower (first thing in the morning) and the unit is set to the mid 70s for higher it will automatically start in the defrost mode. The unit will switch to the dash vents once the outside temp rises and/or I lower the internal setting. If I remember correctly, both my '71 and '79 Cadillacs with the Climate Control did the exact same thing.

    I've had Mickey for a few years now. He just started doing it here recently (past month). It seems like the defrost comes on, then floor, then vents, then somewhere!

  8. #8
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    Quote Originally Posted by tbone View Post
    I like your screen name.....

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  9. #9
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    Quote Originally Posted by ammolance View Post
    That'd be awesome, but I'm down in the panhandle of FL now (Panama City).
    The eatc unit comes out, has to come out to fix anyway, send and get back in a day or two.
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  10. #10
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    Quote Originally Posted by RubberCtyRauder View Post
    The eatc unit comes out, has to come out to fix anyway, send and get back in a day or two.
    That is correct.
    “When you can’t make them see the light, make them feel the heat.”
    Ronald Regan

    "The only way to deal with the Islamic State - these blood thirsty, blood-drunken, terrorists -
    is to kill them, keep on killing them, until you kill the last one, then you kill his pet goat."

    Lt. Colonel Ralph Peters

    “Be polite, be professional, but have a plan to kill everybody you meet.”
    "I come in peace. I didn't bring artillery. But I'm pleading with you, with tears in my eyes, if you **** with me, I'll kill you all"
    General James Mattis




  11. #11
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    Quote Originally Posted by fastblackmerc View Post
    That is correct.

    Sir, I truly appreciate the confidence...but in no way (unless its super painless) do I want to try and remove the eatc (probably botched that acronym up), especially in this car. I don't mechanic, electric, plumb, build, etc. I break stuff - plain and simple. I stick to my job, and am good at it. IF it is an easy removal, I may attempt it with some adult (mechanic friend) supervision, and am otherwise open to any suggestions!

  12. #12
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    There is instructions in the DIY forum and numerous YouTube vids most likely
    2004 SB Ported Trilogy 48
    Has supporting mods and stuff
    Thanks to Marty O for his help in updating this car.

    R.I.P.
    Rex "SC Cheesehead"

  13. #13
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    I thought the EATC defaults to defrost when it craps out. If your system is switching from vent to vent that sounds normal for Automatic mode, in other words the car decides where it needs to send the heated/cooled air most.

  14. #14
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    If there is a complete loss of vacuum, Mr. Man is correct...the system will switch to defrost and stay there, however if there is a small leak, such as from one or more bad o-rings, the system can operate normally at high-vacuum low-load such as idling or just cruising at 40 on a flat road. When load increases, necessitating a further push on the gas pedal, vacuum drops and the system will go wonky. When you return to a cruise situation, or are decelerating, the system regains vacuum levels and begins to operate normally again. This could account for your seemingly "random" changes in the air outlet position.
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  15. #15
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    What local auto parts store would sell genuine ford/mercury parts? Need to fix this today. Digging up the wind shield in the morning into the sun = can’t see!

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