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Where The Heck is The Heater Control Valve???

Discussion in 'The Garage' started by BrianDamage, Dec 1, 2003.

  1. BrianDamage

    BrianDamage 1/2 ton status

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    1987 K5 Blazer, 350, TBI


    When I bought my heater core last year, I looked the parts up on the Autozone website before I went to the store. It came up that it also recommended replacing the heater control valve too, so when I got up there, I bought one.

    Well, I never could find the darn thing to replace it on my truck /forums/images/graemlins/eek.gif

    I talked to dude tonight theat recommend finding & replacing it as a possible fix to my heater woes (it will be the only thing I haven't replaced). He said that on most vehicles, it's located in between the water pump & the firewall, and the heater hose runs in one side & out the other. There's nothing like that on mine. I've looked everywhere under the hood. Can somebody clue me in? (A pic would be MOST excellant).

    Here's what it looks like

    [​IMG]
     
  2. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Maybe it's been missing since you bought the truck- that's why you can't find it?? /forums/images/graemlins/confused.gif

    And maybe the fact that it's not installed is the reason for your lack of heat??? /forums/images/graemlins/confused.gif

    Sorry, I can't help other than the above helpful /forums/images/graemlins/rolleyes.gif questions.....
     
  3. BrianDamage

    BrianDamage 1/2 ton status

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    [ QUOTE ]
    Maybe it's been missing since you bought the truck- that's why you can't find it?? /forums/images/graemlins/confused.gif

    And maybe the fact that it's not installed is the reason for your lack of heat??? /forums/images/graemlins/confused.gif

    Sorry, I can't help other than the above helpful /forums/images/graemlins/rolleyes.gif questions.....


    [/ QUOTE ]

    yeah, that's kind of what I'm thinking, but I want to make sue of where it goes before I put this on one in
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I have never seen one in our trucks.

    Where are your heater lines hooked up now?
     
  5. BrianDamage

    BrianDamage 1/2 ton status

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    [ QUOTE ]
    I have never seen one in our trucks.

    Where are your heater lines hooked up now?

    [/ QUOTE ]

    one goes straight to the radiator (just a regular heater hose), the other goes to the intake manifold, between the tbi & the firewall. It's a hose with a factory fitting on the end of it to screwed into the manifold *(about $70 at the dealer)
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    [ QUOTE ]
    I have never seen one in our trucks.

    Where are your heater lines hooked up now?

    [/ QUOTE ]

    one goes straight to the radiator (just a regular heater hose), the other goes to the intake manifold, between the tbi & the firewall. It's a hose with a factory fitting on the end of it to screwed into the manifold *(about $70 at the dealer)

    [/ QUOTE ]

    It's piped correctly.

    I replaced that fitting long ago with a nipple and some rubber hose on my TBI rig. /forums/images/graemlins/thumb.gif
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Cool! Selling parts for vehicles that never had that part.
    There is no control valve. Coolant always goes through the core.

    What thermostat are you running? 195 is what GM specs. My burb pumps out so much heat when fully warm with 195 that I had to turn it down this morning and there was frost on my windows.

    Blend door may not be properly adjusted.

    Pull Glovebox door. There is a cable coming from the controls to a lever on the top of the box. That is what divertes heated air into the cab. If it's not adjjusted to get full throw or its binding you will have poor heat.

    Also verify that both Vacuum operated flaps are working. One is near the gas peddle on the side of the blower box. It controls floor vent and dash. The second is behind the box almost directly behind the blend door. It controls defrosters. There is a third in the cowel that controls fresh or recirc(max a/c).
     
  8. HarryH3

    HarryH3 1 ton status Author

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    Yep, what Grim said. Our rigs didn't come with a heater control valve. Coolant always circulates through the heater core. /forums/images/graemlins/eek.gif The blend door determines the mixture of heated and non-heated air that comes out the vents. The bad news is that as old as our rigs are, most of them have poor seals on the blend door now. This lets heated air into the cab even in summer. /forums/images/graemlins/angryfire.gif I put a manual valve inline with the heater core on my '75. I shut it in the summer and can tell the difference in the temp of the air coming out of the vents. /forums/images/graemlins/thumb.gif
     

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