good a/c-lukewarm heat

Discussion in 'General Chevy & GM Tech Questions' started by earnhardt724, Nov 25, 2010.

  1. earnhardt724

    earnhardt724 New Member

    have a 1995 silverado with 5.7 engine-the a/c is good.but the heat comes out lukewarm.check hoses and all are warm.temp guage goes up to midway range and the suddenly drops to 160.stays there most of the time,but does raise occasionly to 180,have a 195 thermostat and the anti-freeze is good,anyone have any ideas what the problem could or email

    DAREDEVIL Rockstar 4 Years 1000 Posts

    did u ever replace the thermostat ?? i would say its shot ?? also check for air in the system....mmmhhhh just guessing....

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    The Heater Core is most likely only a small amount of Coolant is flowing through it......Went was the last time the Coolant was Flushed??

  4. stephan

    stephan Rockstar 4 Years 5000 Posts

    Hey Earnhardt, welcome to the GM truck club..
    I agree with both thermostat & heater core ideas above, but the thermostat is the most likely suspect here, because you say your temp guage is fluctuating.. It should not do this. It should rise to 195 degrees F & stay there. Remember, thermostats are to set the minimum temperature of your engine, & they have nothing to do with maximum temperature unless it is stuck closed. It is much cheaper & easier to replace the thermostat than the heater core, so replace it first.

    It is 95% probability that the thermostat is the problem in your case because your engine temp should not go back down to 160 unless the thermostat is opening back up too far & letting too much coolant to pass from the radiator into your engine.
    Last edited: Nov 25, 2010
  5. earnhardt724

    earnhardt724 New Member


    thanks to all for inout,it was the thermostat,all is good now.

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