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89 Blazer -heater help.. what could cause

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rocko, Oct 17, 2002.

  1. rocko

    rocko 1/2 ton status

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    Okay.. ran the heater to see if the truck heat's up.. nothing.. the air temp stay's the same.. full, low, middle no change. The AC is freakin cold.. the temp gauge won't go over 110 degrees.. when i drove the truck home from Houston.. it got up to about 190..
    What prevents heat/hot air from coming through the vents?
    Heater core?
    Thermostat?
    TIA
     
  2. Stoopalini

    Stoopalini 1/2 ton status

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    Check the hose that leads into the heater core, and make sure there isn't a valve on it. I've seen people (and done it myself) put a valve in to bypass the heater core in the summer.....Just a thought.

    If that's not it, maybe your HVAC controlls are messed up like mine are /forums/images/graemlins/wink.gif

    Thomas.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    If the temp gauge isn't moving (most of the time) then you've probably got a thermostat problem. Now of course I'm assuming you are monitoring the engine temp here?

    Without a thermostat, or perhaps with one stuck wide open, your engine may not EVER warm up.
     
  4. rocko

    rocko 1/2 ton status

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    Thanks Dorian and Thomas..
    I'll check both those areas..
    Dorian.. who doesn't monitor their gauges? I alway's seem to glance at them when I'm driving.. /forums/images/graemlins/grin.gif /forums/images/graemlins/thumb.gif
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    I just didn't want to assume you were using an aftermarket gauge for the radiator temp or something else not the temp at the cylinder head. So yeah, if the sender/gauge/wire is good, then you've probably got a thermostat problem.

    If the engine temp is showing as cold after driving, being careful of course, you can pop the radiator cap. If it has no pressure (and the coolant is cold) after driving it for 10-15 minutes, then you've got a thermostat problem.
     
  6. BranndonC

    BranndonC 3/4 ton status

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    I had the same problem, heater wouldn't heat up at all, but i had a new thermostat installed i think a 190 degree one and it heats up fine now, just takes like 10-20 minutes to get max temp. /forums/images/graemlins/smile.gif so i think if you replaced the thermostat it would fix the problem. The part was like $12.
     

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