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Thread: '98 Dodge 5.9L not warming up

  1. #1
    Join Date
    Jan 2009
    Posts
    2

    Red face '98 Dodge 5.9L not warming up

    Hi, hoping someone can help me. I have always enjoyed working on my vehicles myself, and as such, sometimes have problems diagnosing what to fix. My 98 dodge ram 1500 has developed a problem this winter. It will not warm up past about 150 on the gauge (where the lower line starts). The heater blows warm/lukewarm, enough to defrost, but not as hot as it should or used to. I replace the thermostat thinking that could be the only problem. Didn't fix it. Still doing the same thing. It is full of antifreeze. Any ideas of what to check? Also, over the last couple of years my fan blower has been fluxuating when I press down on the accelorator. Still blowing the same speed, but it switches between the defrost vents, and the straight ahead vents. If I let off on the throttle it will switch back to the straight ahead vents. Does that make sense? Once again, thank you in advance for any help.

  2. #2
    Join Date
    Jan 2009
    Posts
    2

    Default warming up

    it sounds to me like you mite have a vacuum line under the dash that is leaking and not letting the heater box open all the way.hopes this helps i had the same problem with my dodge and thats what it was.

  3. #3
    Join Date
    Jan 2009
    Posts
    2

    Default

    Thank you for the advice I believe you are right. The blower has been switching between forward air, and defrost with varied throttle settings for about one year. I definately think that is a vacuum leak under the dash. I also think that the lack of "hot enough" cabin temperatures might be linked to the "mixer" door under the dash, also vacuum I believe. Might be same problem. I am starting to think that the temp gauge might be an isolated unrelated problem, either a sending unit or something of the sort. Thanks again, I plan on looking into it this weekend. A buddy of mine suggested taking a temp reading on the coolant manually, to validate the gauge in the dash. I am aware of the safety issues of doing this, but might try it carefully. By running the truck the whole warm up time with the radiator cap off, then once it's warmed up fully take the temp. We'll see.

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