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(DIY) AC or Heater Only Blowing on HIGH? Here's a fix

Discussion in '2nd Gen. Tacomas (2005-2015)' started by jmanscotch, Apr 1, 2018.

  1. Apr 1, 2018 at 2:08 PM
    #1
    jmanscotch

    jmanscotch [OP] Texan

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    A seemingly common problem with our 2nd Gen Tacoma's is the HVAC system will stop blowing on any fan setting lower than high.

    Any one familiar with this symptom from a different vehicle (cough cough Jeep) will know it's a good sign of a failed Blower Motor Resistor. While it *might* be a bad blower motor resistor in your Tacoma, it might also be due to a bad connection in the plug that connects to the blower motor resistor.

    Toyota has since issued a TSB for an updated Blower Motor Resistor design and calls to replace the connector for it as well.

    If you find this scenario in your truck, you'll need to purchase two pieces for the repair:

    - New updated Blower Motor Resistor - Toyota PN 87138-04052 $30 here on Amazon http://a.co/d/2dAKegO
    - New Connector for BMR - Toyota PN 82141-04M40 $20 here on Amazon http://a.co/d/06vUseE

    [​IMG]


    You'll also need the following tools:

    - 5.5 MM shallow socket (to remove the BMR)
    - Wire cutters/strippers (to replace the connector)
    - Solder, heat gun and shrink wrap -or- crimp connectors (to wire in new connector)

    Let's start by locating the Blower Motor Resistor and its connection.

    Sit in the passenger seat of your truck and look down at your feet, note where the middle of your left foot is. Then, get out and poke your head under the dash in that spot and look for this:

    [​IMG]
    [​IMG]
    [​IMG]

    Unclip the connection and take a look, noting any signs of high heat, melting, burning, or broken wires. On my connector, it wasn't so bad that anything and melted to the extent of deforming, but I was still experiencing intermediate fan speed issues.

    Note the 3rd pin from the left and the discolored connector and pin. This is from a high heat situation and is causing a high resistance connection that sometimes prevents the blower motor resistor from operating properly.

    [​IMG]

    Since the repair replaces both the resistor and the connection, it doesn't matter if your issue is solely one or the other, it's smart to replace both as it's the long term, reliable repair.

    On to the repairs.

    Start by removing the blower motor resistor and replacing it with the new updated designed unit.

    Use the 5.5 mm socket to remove two (2) screws on the BMR

    [​IMG]

    Once the BMR is out, you'll see the difference between old (left) and new (right).

    [​IMG]

    Reinstall the new blower motor resistor and screw it back into place.

    Next is to replace the connector. You'll need to cut the old connector off and either solder the new connection or use wiring crimps to connect it. I prefer soldering, but I realize some folks will need/prefer to use crimps. Toyota's TSB on this repair calls for crimp connectors.

    I cut all four (4) wires pretty close to the base of the connection. I stripped back the insulation on both sets of wires. Here's of picture of that happening.

    [​IMG]

    The wires are color coded, so match the new connector up to the existing truck wiring and solder/crimp them back together. I've already soldered them and have the shrink wrap in place here:

    [​IMG]

    I wrapped the wires up in a little electrical tape for neatness and plugged the connector back into the resistor, ensuring it seats properly and fully.

    Would you look at that...I can now adjust my climate control to an acceptable mid range fan speed!

    [​IMG]


    Cheers.
     
    Last edited: Nov 17, 2018
  2. Apr 1, 2018 at 2:43 PM
    #2
    b_r_o

    b_r_o I always have coffee when I watch radar

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    Another thing to think about is if the blower resistor keeps failing repeatedly. All the current for the blower motor goes through the resistor. If the blower motor starts to get shorted/ partially shorted then it draws more and more current (amps) to perform the same amount of work. It's the extra current that creates the heat that takes out the resistor .

    If the resistor fails once, replace it and don't over think it. But if you get into a situation where you're doing resistors over and over then replace the blower motor (even if it sounds fine, looks fine, etc). You could also check the resistance of the motor windings with a multi-meter and compare with a new one
     
    BandanaBerg and jmanscotch [OP] like this.
  3. Apr 1, 2018 at 3:31 PM
    #3
    Jimmyh

    Jimmyh Well-Known Member

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    Not to be critical, but that isn't what dielectric grease is for.

    Dielectric grease is electrically insulating and does not break down when high voltage is applied. It is often applied to electrical connectors, particularly those containing rubber gaskets, as a means of lubricating and sealing rubber portions of the connector without arcing.
     
  4. Apr 1, 2018 at 5:59 PM
    #4
    jmanscotch

    jmanscotch [OP] Texan

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    You know what, I've never read up on dielectric grease, that's good info to know. I don't mind the correction at all sir, that's what we're here on the forum for, so if my information isn't correct, I'd rather someone bring it up before I misinform others! I've only ever used it in spark plug > boot connections and kinda assumed it was a weather barrier of sorts combined with an electrical connection promoter. I see the latter is not actually the case.

    The problem in the Tacoma is the wire gauge (of the white wire, third pin in the pics) being too small to carry the current without dissipating some of it in the form of heat. Hence my reasoning for looking to lower resistance in the crimp connection as well as offer a heat dissipating medium to help rid the connection of the heat it will inevitably see unless the wire gauge is increased.

    Would you be able to suggest an electrically supportive medium as a replacement?
     
    Bambino likes this.
  5. Apr 1, 2018 at 6:37 PM
    #5
    1Shifter

    1Shifter Well-Known Member

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    Same as everybody else...
    Nice write up, my truck started thus about a month ago. When I hit a bump it works, but another and it stops. Guess I'll be crawling under my dash in the future
     
    jmanscotch [OP] likes this.
  6. Apr 1, 2018 at 6:51 PM
    #6
    b_r_o

    b_r_o I always have coffee when I watch radar

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    https://www.amazon.com/gp/aw/d/B000...abilant+22&dpPl=1&dpID=41ZZORFrGZL&ref=plSrch

    This is designed as electrical contact enhancer in places where the pins are super tiny, like pcm connectors. Might be helpful in larger applications
     
    blu92in99 and jmanscotch [OP] like this.
  7. Apr 2, 2018 at 7:44 AM
    #7
    jmanscotch

    jmanscotch [OP] Texan

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    Looks like good stuff, but $60 is a bit steep. What about something like this: http://a.co/6z070UH
     
  8. Apr 2, 2018 at 8:40 AM
    #8
    Jimmyh

    Jimmyh Well-Known Member

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    This has been a subject for quite a while and the actual cause is a loose fit on the female to male terminals increasing the resistance and acting as a heater. Then the heat exaggerates the problem and makes it looser...

    I have found that replacing the plug will work wonders, I have also used a method in other applications where I slightly tin the male terminal with solder making it thicker and getting a tighter fit.
     
    JGO, Skyway and jmanscotch [OP] like this.
  9. Apr 2, 2018 at 10:20 AM
    #9
    jmanscotch

    jmanscotch [OP] Texan

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    I didn't realize it had been discussed in depth, I haven't found that thread. The information I found on the topic seemed to show a common theme with the white wire, with blue stripe, being the one that tended to get hot. With it being the common denominator and not typically the other 3 wires, that are fashioned in the same manner, one would presume it was an inadequate wire gauge issue rather than a loose fitting connection issue. If it was a loose connection issue, wouldn't the other 3 exhibit the same symptoms? No arguing here, just attempting to understand fully.
     
    MrKatanga likes this.
  10. Apr 3, 2018 at 1:46 PM
    #10
    Jimmyh

    Jimmyh Well-Known Member

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    The white wire with the blue stripe always sees full current before it goes through the resistance bridge regardless of which speed is selected. The other wires only see current flow as determined by the speed selected. As you can see from the drawing below the blower motor always has 12 VDC applied to it when you energize the switch for the blower the resistance controls current flow to ground. The white wire with a blue stripe always has current when the blower is running, the other wires see a reduced current only when it is running on that speed.

     
  11. Apr 8, 2018 at 7:25 PM
    #11
    CaptQuinn

    CaptQuinn Well-Known Member

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    jmanscotch! I'm so fixing my blower motor connection when I get back to my truck in a few days. Looks super simple, and I've been dealing with this intermittent fan operation for about 3 years on my 2013 Taco. Had the deal charge me $350 to swap out my motor and relay....that lasted about a month. Grrr.....
    I'll let you know how it works.

    :cheers:
     
    jmanscotch [OP] likes this.
  12. Apr 9, 2018 at 8:22 AM
    #12
    jmanscotch

    jmanscotch [OP] Texan

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    Right on man! Hopefully it's the fix for you.

    Mine's been working great since, which has made the lady friend and I very happy.
     
  13. Apr 15, 2018 at 9:57 PM
    #13
    CaptQuinn

    CaptQuinn Well-Known Member

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    Yup, mine is fried too. Just ordered the parts you listed!
    Thanks Man.
     
    jmanscotch [OP] likes this.
  14. Jul 22, 2018 at 7:56 AM
    #14
    #tacobutt

    #tacobutt New Member

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    This was great. Thank you for posting this. I've never soldered before and I go this done. Links were great, product shipped quickly and I am cool as a cucumber, which is important living in Florida. Thanks again!!
     
    Skyway likes this.
  15. Jul 22, 2018 at 8:21 AM
    #15
    CMD-KY

    CMD-KY Well-Known Member

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    Has anyone tried DeOxit products on the connectors? They have a cleaner cleaner and conditioner in various methods of application.
     
  16. Jul 23, 2018 at 11:50 AM
    #16
    Tacoman1992

    Tacoman1992 Active Member

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    Amazing write up.
     
  17. Jul 23, 2018 at 11:50 AM
    #17
    Tacoman1992

    Tacoman1992 Active Member

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    Just fixed mine I got one off Amazon for $22 and it worked like a charm.
     
    wannabemtnbiker likes this.
  18. Jul 23, 2018 at 11:50 AM
    #18
    Tacoman1992

    Tacoman1992 Active Member

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    OEM quality as well
     
  19. Jul 23, 2018 at 11:51 AM
    #19
    Tacoman1992

    Tacoman1992 Active Member

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    Only thing I noticed is that AC doesn't blow as strong but it does work on all levels now
     
  20. Jul 23, 2018 at 11:52 AM
    #20
    Tacoman1992

    Tacoman1992 Active Member

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    FYI I'm a bit clueless on doing repairs but I searched for this AC resistor for a solid hour on the drivers side because I thought it said it was around there however, it is on the PASSENGERS SIDE lol
     

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