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AC not cutting off...

Discussion in '2nd Gen. Tacomas (2005-2015)' started by twhditto, Oct 13, 2020.

  1. Oct 13, 2020 at 5:58 AM
    #1
    twhditto

    twhditto [OP] Member

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    I just purchased a 2012 Tacoma, prerunner. Have been getting it up and going and discovered that the AC does not shut off. The light on the AC button goes off, but it still blows cold air. The Max AC is off as well. Does it sound like a relay or somethings? Or am I missing something??? Thanks in advance.
     
  2. Oct 13, 2020 at 6:24 AM
    #2
    Fullboogie

    Fullboogie Well-Known Member

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    There is a relay under the hood. If it goes bad it can cause the compressor to run constantly. Look under the hood while the engine is running and see if the compressor is cycling properly.
     
  3. Oct 13, 2020 at 6:57 AM
    #3
    DG92071

    DG92071 Well-Known Member

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    If you have the control in the defrost position the AC stays on and the AC light is off. Apparently the AC light isn't a power light any more.
     
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  4. Oct 13, 2020 at 10:00 AM
    #4
    twhditto

    twhditto [OP] Member

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    I checked all of that and that is not the problem. it is crazy. I will check the relay under the hood. Thanks!!!
     
  5. Oct 13, 2020 at 10:29 AM
    #5
    Fullboogie

    Fullboogie Well-Known Member

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    Following up, I had a bad relay on my 4Runner that caused the same problem - the compressor would not turn off. It ended up icing up the evaporator under the dash on a long trip which cut off all air flow in the cabin. That's how I discovered it. If you pop the cover off the relay you will see a set of points - like an old distributor - where the contacts have welded themselves together. That keeps the compressor from cycling.
     
  6. Oct 13, 2020 at 10:59 AM
    #6
    Fullboogie

    Fullboogie Well-Known Member

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    Here's the relay, upside down, with the body removed. In the lower left hand corner you can see the points I referred to.

    [​IMG]
     
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  7. Oct 13, 2020 at 2:22 PM
    #7
    twhditto

    twhditto [OP] Member

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    I am headed to the auto place in a bit. $20. Thanks!!!
     
  8. Oct 13, 2020 at 9:08 PM
    #8
    Jimmyh

    Jimmyh Well-Known Member

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    The relay in question would be the MG CLT Relay ( magnetic clutch relay ) under the hood fuse/relay panel.

     
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  9. Oct 13, 2020 at 10:49 PM
    #9
    Muddinfun

    Muddinfun Well-Known Member

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    So, if the relay contacts are welded, wouldn’t the battery go dead overnight?

    Have you even confirmed that the compressor is turning constantly?

    Have you checked the coolant in the radiator? Is the temp gauge in the middle?
     
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  10. Oct 14, 2020 at 1:04 AM
    #10
    Jimmyh

    Jimmyh Well-Known Member

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    All good questions that need answers before throwing money at it.
     
  11. Oct 14, 2020 at 4:57 AM
    #11
    twhditto

    twhditto [OP] Member

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    I threw the $20 at it last night. Fixed the problem. I pulled the old relay with my fingers. I will dissect it today but one of the ends is crushed inward! The ac no longer runs all the time. Thanks everyone.
     
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  12. Oct 14, 2020 at 5:11 AM
    #12
    Jimmyh

    Jimmyh Well-Known Member

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    What crushed the relay?
     
  13. Oct 14, 2020 at 5:32 AM
    #13
    twhditto

    twhditto [OP] Member

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    It appears that the relay itself was ok mechanically. I cut off the plastic top and it moved fine. But it appears that someone used some sort of pliers or something and crushed the ends and the cover smashed in on the contacts. Craziest thing I have seen in a while.
     
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  14. Oct 14, 2020 at 5:47 AM
    #14
    Jimmyh

    Jimmyh Well-Known Member

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    That is what I thought when you said it was crushed... Seen it before.
     
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