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Temperature Guage bouncing

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by ROCKTA, Nov 14, 2013.


    ROCKTA New Member

    The guage has been moving from normal (190) to 230 and then to 160 and then back to normal. Today the heater stopped blowing heat. Whats wrong? Thermostat?
  2. BurbanMan

    BurbanMan Member

    edit: I managed to overlook the part about the heater.... Definitely swap out the thermostat as that will be the least expensive place to start. If that doesn't fix it, I would have a coolant system diagnostic done. That can usually happen for about $30
    Last edited: Nov 14, 2013
  3. Pikey

    Pikey Moderator Staff Member 1000 Posts

    If it stopped blowing heat I would suspect that the thermostat is moving slowly. But, there can be many other causes for it to stop blowing heat.
  4. BurbanMan

    BurbanMan Member

    you don't recon his sending unit and blend door actuator both went bad about the same time do you?
  5. Pikey

    Pikey Moderator Staff Member 1000 Posts

    It is highly unlikely that they both went at the same time. It could be anything from air in the system to a clogged heater core, a bad sending unit, a bad stepper motor.

    Wait a second... What year and model truck are we talking about here? Is it rapidly bouncing or does it get to the operating temp then slowly drop?

    ROCKTA New Member

    1996 1500

    It is 1996 1500 GMC. The temp guage moves slowly. It will start off at 190 them run up to 230 and stay there a while then drop back down (liek if thermostat finally opened). It will do this often. Then today the heater wouldn't work but was still blowing cold air.

  7. Pikey

    Pikey Moderator Staff Member 1000 Posts

    I would change the thermostat, they are cheap! While you are at it you might as well do a coolant flush and change the radiator cap.

    ROCKTA New Member

    Have new thermostat in hand. Will be changing tonight. I'll let y'all know tomo. Thanx
  9. poncho62

    poncho62 Member

    Your antifeeze level is low......
  10. BurbanMan

    BurbanMan Member

    thats actually a good pointer.

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