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Balky Heater Control. Valve or Cable (or Knob)?

Discussion in '1st Gen. Tacomas (1995-2004)' started by MainerDave19995VZ, Jul 21, 2018.

  1. Jul 21, 2018 at 12:43 PM
    #1
    MainerDave19995VZ

    MainerDave19995VZ [OP] Well-Known Member

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    David
    Maine
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    1999 Tacoma Extra Cab SR5 TRD 5 Speed 5VZFE
    2nd generation 16" wheels with 1.25" BORA spacers
    So, my heater control knob has been clicking (cable slipping?) when I get about 75% of the way to full heat. I could wiggle it and get full heat with a little effort. Now it quits at about 30% to full heat. I had to pop the hood and move the valve manually at the end of winter. Bad cable, bad valve, or bad knob? Or a combo or those options? Anyone dealt with this? I have yet to rip into the dash for anything yet. Figure I'd work on it now instead of in December.

    IMG_3731.jpg IMG_3732.jpg
     
  2. Jul 21, 2018 at 12:50 PM
    #2
    BillsSR5

    BillsSR5 Well-Known Member

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    looks like the cable is rubbing on that hose below it
     
  3. Jul 21, 2018 at 12:56 PM
    #3
    MainerDave19995VZ

    MainerDave19995VZ [OP] Well-Known Member

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    2nd generation 16" wheels with 1.25" BORA spacers
    That's an optical illusion due to camera angle.
    IMG_3733.jpg
     
  4. Jul 21, 2018 at 1:00 PM
    #4
    BillsSR5

    BillsSR5 Well-Known Member

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    maybe you can have someone work the knob in the truck, while you observe whats happening in the engine bay, I would guess the cable might be bound up,but I think it also connects to something inside the truck under the dash I assume couldn't hurt to find the other end to see if theres a issue there
     
  5. Jul 21, 2018 at 1:05 PM
    #5
    KactusJack

    KactusJack Well-Known Member

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    Collettsville, N.C.
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    Pull the knob off and check the back that slides over a shaft. It may be broken or worn, causing the clicking noise and failure to turn the shaft.
     
  6. Jul 21, 2018 at 1:16 PM
    #6
    BillsSR5

    BillsSR5 Well-Known Member

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  7. Jul 22, 2018 at 9:16 AM
    #7
    skeezix

    skeezix Well-Known Member

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  8. Aug 19, 2018 at 11:53 AM
    #8
    MikeWH

    MikeWH Well-Known Member

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    Colfax, CA
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    I had almost same problem. Eventually the cable sheath broke at the control valve.
    Step one- adjust the clamp of the existing cable at the heater control valve. Maybe this will fix it. Didn't for me-
    So I bought a new cable ($12 I think) and went to work replacing it. Get ready for about half a day. You will need to remove your heater control assembly from the dash a few inches, then take a few layers of parts off it. Changing the cable is relatively easy. WHILE YOU ARE IN THERE- Get some high quality grease and clean and grease the gears, detents, etc. Also a good time to replace the 2 light bulbs (#74 with a green condom on them).
    After I got my old cable out, it was clear it was bound up and had a lot of friction.
    Now my heater adjustment feels brand new!
     
  9. Sep 16, 2018 at 5:59 AM
    #9
    MainerDave19995VZ

    MainerDave19995VZ [OP] Well-Known Member

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    1999 Tacoma Extra Cab SR5 TRD 5 Speed 5VZFE
    2nd generation 16" wheels with 1.25" BORA spacers
    Thanks a lot for this Mike!

    So I finally got around to the diagnosing stage today. First I unclipped the cable at the valve and took the cable off the valve. No tools required. And the clip is captive so it doesn't fall into the engine compartment! The valve moved very easily by hand. Went into the cab and tried the hot cold knob. Still got about 30% towards hot and then click, click, click. Pulled the knob off and looked in and everything in there is just stops and detents. Nothing you can see is making the clicking sound. So it is internal plastic gears that are clicking I'm assuming. I can push the knob in hard and turn it and it works the cable without clicking. So I go attach the cable again and try the push the knob hard trick and NO DICE. It starts clicking/slipping at the same point. So my analysis is that the cable started to bind up and over a few years I forced the gears too hard and then they started to fail. I'm inclined to buy the cable AND the control unit/assembly since I'll be deep enough in there that I'll probably kick myself if I have to do it twice. Am I missing something? Parts with shipping are $145.00 or so.
     
  10. Sep 16, 2018 at 10:39 AM
    #10
    MikeWH

    MikeWH Well-Known Member

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    Colfax, CA
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    Glad to help- I had similar symptoms with the clicking at the end of travel on my hot/cold knob. I believe this is the gears skipping, but they aren't necessarily ruined. The whole assembly is weak enough that given enough resistance, when you are turning the knobs, other parts start flexing and this allows the gear teeth to slip past each other. It sounds horrible, but it doesn't mean anything is permanently broken. In my case all of the drag causing this was due to dirt/wear inside the cable sheath. You can rule that out if you want-

    Before you drop money on an entirely new control unit (and if you go to the trouble of that, you are looking at a lot of work to get all 4 cables disconnected. I would buy all 4 cables and replace them given the hassle involved!)- Try disconnecting the cable (at the control unit) for the hot water valve and see how things feel at that point. You will probably have to disconnect one cable above it to get access (I believe this is the fresh/recirc cable). While you are in there, clean and lube both sets of gears and all other moving parts with a high quality grease. Also clean/grease all the moving parts going into the air box under the dash (I use
    Super Lube 21030). See if that makes things better before you replace the entire control unit. At that point, if you have the hot/cold cable on hand, it's 5 extra minutes to replace it by sliding it out from the engine compartment towards the interior, and sliding a new one back in and reconnecting and re-adjusting (at the valve) for proper operation.

    Hope this helps, glad I can share some of my experience on here!
     

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