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Heater not blowing hot just luke warm..backflushed the heater core. should I try new thermostat?

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  • Cars & Trucks Master
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Is the engine getting to full operating temperature? Can you feel the hoses going into the heater core, are they cooler than the other radiator hoses? Do you have an inline water valve for the heater on the vehicle? If your engine is reaching full operating temperature then changing the thermostat will gain you nothing. If your hoses going to the heater core are not as hot as the other hoses you still have a blockage in the system somewhere, if you have a heater valve in line somewhere, make sure it is operating. Without knowing what vehicle it is you are working on it makes it more difficult to try and help.

Posted on Nov 15, 2014

  • 3 more comments 
  • Joe McQuaid
    Joe McQuaid Nov 15, 2014

    Hi Dan..its a 99 cherokee sport 4.0 The 2 hoses from heater core are hot...its up to temp I believe. The top radiator hose however is cold

  • Joe McQuaid
    Joe McQuaid Nov 15, 2014

    both blower fan and radiator fan seem to be valve on the hose changed thermostat and waiting to see what happens

  • Joe McQuaid
    Joe McQuaid Nov 15, 2014

    Ok....blows hot/cold as it should....not as hot as I think it should but better. Next Q...Has a 16lb radiator cap with pressure relief valve..should I go small? Like maybe a 10 or even 7lb?? Thanks to everyone as well for the input

  • Joe McQuaid
    Joe McQuaid Nov 15, 2014

    And if anyone is willing to speak on phone with me to save time you could email your # to me Thanks again

  • Joe McQuaid
    Joe McQuaid Nov 15, 2014

    Motor is working fine ty



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Posted on Jan 02, 2017

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SOURCE: car warms up just fine but the heater blows cold air

both hoses is hot signifies thatcoolant circulation is just fine check the blend door actuator it might be stuck.pan the heater temp controller from hot to cold do you feel any change in temp of the air from the blower?if you dont feel any change check the blend door actuator

Posted on Jan 17, 2010

  • 1055 Answers

SOURCE: heater doesnt get hot

is their a control valve in the heaater hose?
if so it could be stuck

Posted on Mar 04, 2009

  • 6674 Answers

SOURCE: Heater is blowing luke warm heat

Double checking, does fun shut off when switched to heat instead of defrost?

Posted on Jan 24, 2009

  • 162 Answers

SOURCE: we have an audi a4 2.6cc , the heater only blows

sounds like the thermostat is not functioning correctly? either that or not in at all? thus making the water which would normally warm up quickly, warm up extremely slowly and on really cold days not at all? with a 2.6 engine your car shoudl warm up in record time?

Posted on Mar 04, 2009

  • 30 Answers

SOURCE: Heater blows only luke warm air.

check control swicth

Posted on Feb 12, 2010

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