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Defrost engages AC compressor

Discussion in '2nd Gen. Tacomas (2005-2015)' started by Tremelune, Jul 26, 2009.

  1. Jul 26, 2009 at 2:06 PM
    #1
    Tremelune

    Tremelune [OP] Member

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    Driving around last night, I noticed that every time I turned the heat on, I felt a slight but sudden loss of power. I couldn't figure it out. The AC light was still off, but something felt wrong.

    Then I tried turning the heat on and off on different settings and realized it only happened when air was being sent to the windshield. It then occurred to me that conditioned air is dry and helps with defrosting... Pretty clever.

    Maybe this is how all cars are these days, but I spent about twenty minutes thinking I was going to have to fix some gremlin with the AC...Just figured I'd mention it, in case someone is getting bad gas mileage from having the heater set on feet/windshield all the time...
     
  2. Jul 26, 2009 at 2:09 PM
    #2
    TRDKenE

    TRDKenE DAMN GOOD DEAL!!

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    this is pretty much how vehicle have been for sometime...take the humidity out of the air..thus no fog...
     
  3. Jul 26, 2009 at 2:16 PM
    #3
    Tremelune

    Tremelune [OP] Member

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    This was on a 2009... The next newest car I've ever had was 1996. The world, she is a-changin'...
     
  4. Jul 26, 2009 at 2:30 PM
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    moto932

    moto932 What's the matter, Colonel Sandurz? CHICKEN?

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    5100's @ 1.25", Scangaugae II, deck plate mod w/AFE Pro Dry S filter, grey wire mod, alarm mod, defrost w/o compressor mod, de-badged, 17" sport wheels powder coated black, 1" B.O.R.A. wheel spacers, 265/70/17 Cooper Zeon LTZ's, sockmonkey beside decals.
    correct me if im wrong but i think there are write-ups in the diy forum on how you can make the defrost run without having the compressor run. this makes it nice because most of the time i need it i dont need the compressor to run and kill my mpg. then if you do need the cool dry air you just puch the ac button and it comes on. i believe there are writ-ups for both 1st and 2nd gens too.
     
  5. Jul 26, 2009 at 2:38 PM
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    Tremelune

    Tremelune [OP] Member

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    Nice. I may just do that. This truck is thinking too much.
     
  6. Oct 14, 2013 at 6:13 AM
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    airlandsea

    airlandsea New Member

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    Does anyone know how to deactivate the ac compressor running with the defrost on a 2nd gen (2013) 4 cyl.
     
  7. Oct 14, 2013 at 7:50 AM
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    bjboucher

    bjboucher Mama says Tacoma World is da devil!

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  8. Oct 14, 2013 at 7:50 AM
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    rustbus

    rustbus Well-Known Member

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    i cant remember the source, but i was given the information that automakers have the AC come on while defrost is selected in order to ensure the AC pumps/systems get a little use during winter months when they are turned off for long periods - in order to keep the seals from drying out.

    my coworkers dodge diesel does the same thing

    I personally feel the defrost setting is the devil and I keep my dial away from it as much as possible - so I don't encounter this AC pump kicking on problem much
     
  9. Oct 15, 2013 at 6:02 AM
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    airlandsea

    airlandsea New Member

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    Unfortunately I must use my defrost daily up here in Central NY and really would rather not run the A/C. I realize that it is good to turn it on a few times during the winter to keep the seals conditioned but the fact that it automatically engages with defrost as well as with turning the temp dial all the way to cold really bugs me. The 2.7 bogs down every time I turn on the fan as defrost is my default setting...:mad:
     
  10. Oct 15, 2013 at 6:41 AM
    #10
    Sloth

    Sloth Baby Ruth?

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    You need the ac to dry the air so it actually de fogs the window. Otherwise you are blowing humid air onto the window which doesn't help
     
  11. Oct 15, 2013 at 6:52 AM
    #11
    KB Voodoo

    KB Voodoo Well-Known Member Vendor

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    Bed Crossbars, tailgate cap, side rails.
    If running the AC is too much for your engine, then you probably should have gotten the V6...

    If running the AC is too much for your wallet, then you probably should have gotten a Corolla...
     
  12. Oct 15, 2013 at 7:12 AM
    #12
    BamaToy1997

    BamaToy1997 ASE Master Tech Vendor

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    THE AC compressor engaging in defrost has been that way since the defrost option was available. I don't know about the 60s, but I know in the 70s that was how it worked. So yes OP, your 1996 did the same thing. You just didn't notice it. You cannot defog or defrost a windshield with humid air. It has to be dehumidified, which is what your AC system does to the air. It first dries it, then the heater core will heat it.
     
  13. Oct 15, 2013 at 8:48 AM
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    Brodie

    Brodie Gear Jammer

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    How does the defrost/defogging work on Cars or Trucks without AC? My first 2 vehicle didn't have a compressor, and the defroster setting worked.
     
  14. Oct 15, 2013 at 8:53 AM
    #14
    kingston73

    kingston73 Well-Known Member

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    This.

    I don't understand some of the "issues" people come up with here. :rolleyes:
     
  15. Oct 15, 2013 at 9:00 AM
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    KB Voodoo

    KB Voodoo Well-Known Member Vendor

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    Bed Crossbars, tailgate cap, side rails.
    By blowing heat on the window. AC is just more effective, because it removes moisture.
     
  16. Oct 15, 2013 at 9:56 AM
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    Brodie

    Brodie Gear Jammer

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    Ok just making the point that you don't "need" the compressor to run, in order for defrost to work.
     
  17. Oct 15, 2013 at 9:59 AM
    #17
    KB Voodoo

    KB Voodoo Well-Known Member Vendor

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    I would prefer it to run when the defrost is on. It keeps the "musty" smell down.

    AC/dehumidification is a good thing, and it's not a big parasitic loss.
     
  18. Oct 15, 2013 at 10:14 AM
    #18
    Brodie

    Brodie Gear Jammer

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    I agree, but having control on when it runs and when it doesn't when blowing air on the windshield isn't necessarily a bad thing.
     
  19. Oct 15, 2013 at 10:24 AM
    #19
    OZ-T

    OZ-T Quite an experience to live in fear , isn't it ?

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    Normal
     
  20. Oct 15, 2013 at 10:36 AM
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    WV150

    WV150 Well-Known Member

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    If you do not want the AC compressor to run when in defrost mode but still want it to cycle some to keep the compressor exercised try running a wire from your back up lights to a relay to kick it on while in reverse. It will get exercised every day a little unless you never back up and you will be able to run in defrost all the time without running the compressor. I always like to run split between floor and windshield.
     
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