Freightliner Columbia 2003 not enough heat

Discussion in 'Freightliner Forum' started by Hardworker, Dec 9, 2012.

  1. Hardworker

    Hardworker Light Load Member

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    Seems like the only way I can get heat is with the recirculation on...Heater core flushed.
     
  2. snowwy

    snowwy Road Train Member

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    the water temp of your truck running cold.

    the temperature control door not fully in hot position. there is some type of blend door that controls the temp. swings from cold to hot to cold.

    some trucks even have a valve that works in conjuction with the blend door. it's a water valve. as you move the temperature to cooler. the door moves to a cooler position and the water valve starts closing. (blocking off water flow to the heater core).

    put your hands on the heater core hoses. one hose should be pretty hot. indicating hot water flow to the core. the other hose should be cold. if it's close to as hot as the other hose. then the heater core is plugged.

    if both hoses are cold. your not getting water flow from the engine. some trucks have some type of watre shut off valve also. follow the heater hoses to the engine and make sure the valves are fully open.

    the heater core works the same manner as the radiator. hot going in. cold going out. if the out is as hot as the in. the core is plugged and not cooling the water down like it should. you get your heat from the heater core.

    others will chime along with other ideas to check.
     
  3. jbourque

    jbourque Heavy Load Member

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    what is your engine water temp running. if you have a 12.7 detroit engine with a lot of miles,you could have a thermostat problem. that seems to b a common problem with them. however it could be a number of other things too. hope you find the problem jon
     
  4. Pablo-UA

    Pablo-UA Road Train Member

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    sounds like a simple problem with thermostat. easy to fix
     
  5. Hardworker

    Hardworker Light Load Member

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    I dont think it is a thermostat problem, temp gauge reads right around 180 when in motion and just idling 600rpm if I crank it up to 1000rpm then it may reach up to 200 then fan kicks on and goes back to around 180, lower hose of the radiator is hot, I think that is enough to rule out the thermostat, as far as the blend door is wide open, I can find any water valve between the heater core and the hoses.. thiis is a freightliner columbia 2003 with mbe 4000..
     
  6. McDaniel Trucking

    McDaniel Trucking Light Load Member

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    I know a buddy of mine had the same problem and one of the valves were hidden behind the frame on the passenger side by the water pump
     
  7. jbourque

    jbourque Heavy Load Member

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    mcdaniel trucking had forgotten about that valve it was a lever type by the frame and water pump. a lot of guys would open it only part way. then they would not have to keep opening and closing the valve.
     
  8. snowwy

    snowwy Road Train Member

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    i can't see full heat with the valve only part way open.

    i leave em open year round. doesn't make sense but the a/c blows couple degrees cooler.
     
  9. nobodyinacoma

    nobodyinacoma Bobtail Member

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    Been having the same problem. Been a cold winter. Changed radiator, flushed core, blend door working properly. No outside valves. You get a 'brief' feeling of hot air, then cold. Bunk is sometimes semi warm. Glad most of the cold is over. Thanks for listening.
     
  10. jhovah

    jhovah Bobtail Member

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    did anyone ever figure out what was the problem with the heat?.....i have a 06 columbia with a Detroit with the same problem..no heat but bunk heat is fine..NO valve by water pump, but both heater hoses are HOT N heater door is moving freely n that motor works fine....ALSO i have the bunk interrup switch in the dash disconnected bc i need a new switch but dont think that has anything to do with it...
    PLEASE HELP.....
     
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