Heat for 2003 Cts
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Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, Heat for 2003 Cts in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; I am having trouble with my heat on the driver side. When idling or driving at slow speeds it is ...
  1. #1
    eddiejager is offline Cadillac Owners Member
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    Heat for 2003 Cts

    I am having trouble with my heat on the driver side. When idling or driving at slow speeds it is warm in the car but when I travel on the highway it gets really cold. Any idea what it could be?

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    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: Heat for 2003 Cts

    This question has nothing to do with warranty or recall information. Moved to CTS............

  4. #3
    josney's Avatar
    josney is offline Cadillac Owners Connoisseur
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    Re: Heat for 2003 Cts

    lots of folks have had this issue and many have been able to solve the problem by flushing the heater core. just do a search within this forum for "heater core"

  5. #4
    Kingoftypos is online now Cadillac Owners Master
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    Sounds like you have a thermostat that is stuck opened.

    KOT

  6. #5
    ghettomike's Avatar
    ghettomike is offline Cadillac Owners Master
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    Re: Heat for 2003 Cts

    Quote Originally Posted by josney View Post
    lots of folks have had this issue and many have been able to solve the problem by flushing the heater core. just do a search within this forum for "heater core"
    its a uphill battle..
    last year i could flush the core and it would work for about a week, this year i flushed the entire system a few times and a few diferent ways... 100% coolant dump and refill 3x... its starting to not be warm again.
    im going to flush just the core out again tomorrow and see how it goes.

  7. #6
    Kingoftypos is online now Cadillac Owners Master
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    Quote Originally Posted by ghettomike

    its a uphill battle..
    last year i could flush the core and it would work for about a week, this year i flushed the entire system a few times and a few diferent ways... 100% coolant dump and refill 3x... its starting to not be warm again.
    im going to flush just the core out again tomorrow and see how it goes.
    Someone mentioned last week or before that they were having the same problem. After flushing it a couple times he gave up and took it to a pro. The pro said that nothing but clean fluid came out. However, they did notice that the secondary water pump was unplugged. Of course they didn't see that until afterwards. I believe the member said its been working since.

    Where this secondary water pump is, I have no idea exactly. But apparently it's with insight of the core hoses.

    KOT

  8. #7
    Cadillac Cust Svc's Avatar
    Cadillac Cust Svc is online now Cadillac Customer Service
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    Re: Heat for 2003 Cts

    Eddiejager, I hope the community DIY feedback has been helpful to you so far! If you would like me to check my GM resources for any relevant information, please send me an email anytime at Katie_Lucille@gmexpert.com. I'm happy to research for you, and including the last eight of your VIN in your message would help my research greatly.

    Best,

    Katie
    Cadillac Customer Service

  9. #8
    voodoochikin04's Avatar
    voodoochikin04 is offline Cadillac Owners Fanatic
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    Re: Heat for 2003 Cts

    secondary electrical pump "after boil pump" is on passenger side of the engine, above the exhaust manifold, in line with the heater core hoses.

  10. #9
    drknt03 is offline Cadillac Owners Member
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    Re: Heat for 2003 Cts

    Try reverse flushing your heater core. I just take a garden hose hook it up to the outlet side you'll be suprise what comes out. Then do it from the inlet side do this two to three times until all or any residue comes out.

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