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Heater Help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by K1Orion, Dec 9, 2003.

  1. K1Orion

    K1Orion 1/2 ton status

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    Ok, my heater don't work.
    The fan blows cold air, I swapped out the 160*thermostat for a 195* and the radiator is full.

    What else is wrong? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
    Can a heater core get plugged up like a radiator, this thing worked awesome last winter.

    The only thing I can think of is that this summer when I did my 350 to 465 swap I had the dash off to help me see things. I removed some of the A/C ducts , maybe I removed something necesary to the heater.Any body have pics of what the heat portion of an A/C setup looks like? Or even a good description would help. /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/deal.gif /forums/images/graemlins/1zhelp.gif

    Any other ideas on wht my problem is(with the heater)? /forums/images/graemlins/ears.gif /forums/images/graemlins/ears.gif
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    Make sure that the cable that opens and closes your heater door under the dash is still connected correctly. That was my problem after I replaced my heater core. The cable popped off and I only had hot air all the time.

    I am sure a heater core could get plugged up too. It is just a small radiator.
     
  3. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Maybe your heater valve is stuck closed.
     
  4. K1Orion

    K1Orion 1/2 ton status

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    heater valve? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
    I'm listening!! /forums/images/graemlins/ears.gif /forums/images/graemlins/ears.gif
    Where is it and how do I check/fix it?
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Don't bother looking. You won't find it. /forums/images/graemlins/eek.gif Our trucks don't have a heater valve. Coolant always circulates through the heater core. /forums/images/graemlins/shocked.gif
     
  6. Kyle89K5

    Kyle89K5 1/2 ton status

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    Flush the heater core with a water hose. Chances are, it will start working again. At least that's what I have to do to mine EVERY YEAR about right now. Without fail, it will get plugged. One of these days, I'll fix it /forums/images/graemlins/rolleyes.gif
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    Don't bother looking. You won't find it. /forums/images/graemlins/eek.gif Our trucks don't have a heater valve. Coolant always circulates through the heater core. /forums/images/graemlins/shocked.gif

    [/ QUOTE ]
    Are you sure? Other opinions? I am pretty sure there is because if hot coolant alway flowed through than whenever you turned on the blower you would get hot air.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Harry is right...

    Rene
     
  9. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif,hmm that brings a new question to my porb, when I hook up my heater hoses back up to the heater core my motor gets hot. /forums/images/graemlins/confused.gif
     
  10. HarryH3

    HarryH3 1 ton status Author

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    The blend door determines the temp of the output air. In the full "cool" position, it blocks air from passing through the heater core. /forums/images/graemlins/thumb.gif
     
  11. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    That is what I was thinking after I read your's and rustbuckets post. I think the cable that activates that flap is broken in my truck along with my current heating problem that I can't figure out. How hard is it to replace the cable?
     
  12. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Your heating system is vacuum controlled. Make sure that you have vacuum at you blend door. Without it, the door will stay shut and you'll get no hot air into the cab.
     
  13. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I'm getting hot air, the problem is the temp. gauge goes strait fo the red with the heater hoses connected, I have a post in the garage describing it very well.
     
  14. K1Orion

    K1Orion 1/2 ton status

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    I was thinking it was something with the door to regulate temp. I have to look tomorrow or this weekend maybe.

    The "heater valve" sounded suspicious, kinda like blinker fluid or muffler bearings. /forums/images/graemlins/rolleyes.gif /forums/images/graemlins/rolleyes.gif
     
  15. K1Orion

    K1Orion 1/2 ton status

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    Kyle, do you remove the core to flush it and clean between the fins for some reason? Or just flush it out by hooking water pressure to the hoses?
    I'm goona try this first.
     
  16. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]

    The "heater valve" sounded suspicious, kinda like blinker fluid or muffler bearings. /forums/images/graemlins/rolleyes.gif /forums/images/graemlins/rolleyes.gif



    [/ QUOTE ] blinker fluid /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif We have a 76' C30 and far as I know it has a heater valve and I just figured it was the same setup in my 85. Except for the blower.
     
  17. Kyle89K5

    Kyle89K5 1/2 ton status

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    I unhook the line from the radiator and the line from the heater core. Flush back and forth between these two until I get clear water both ways. Hook it back up and see how it feels. /forums/images/graemlins/grin.gif
     
  18. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Pull the glove box door. The flap that turns on and off the heat is on the top of the box right there. I bet the cable has poped off there or at the control.
     
  19. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    ok, thanks
     
  20. K1Orion

    K1Orion 1/2 ton status

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    What a F ing mess!! Spaghetti of hoses eveywhere!! /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif

    Part of the problem was I had it hooked up to a vacuum source that only pulled vacuum when you tip into the throttle.( Front left bottom of a Q-jet) /forums/images/graemlins/rolleyes.gif /forums/images/graemlins/rolleyes.gif

    I pulled the glove box and ashtray off to see what was back there and what the problem was. Defrost ducts aren't hooked up, that would explain its poor performance. The bracket that holds the cable for the door that controls heat/defrost or vent was broke. (Little white plastic thingy inside duct) Made a new one from some thin sheetmetal. Now it completely shuts off the vent and all air goes to the floor or defost like intended. Air still doesn't get hot, gonna have to flush the heater cor and possibly change it.

    Question: On an A/C truck, when should the vents in the kick panels open? I tried evey position on the controls and neither side ever opened.
     

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