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    Heater help

    I need some input on my heater problem. I've spent a couple hours today researching on this forum.

    Here's the situation: no heat at all.

    The thermostat is new and is correctly oriented and installed.
    EDIT: I forgot to mention I'm running fan delete on the engine - did the mod to the electric fan switch to have low speed on all the time and high speed to kick in at normal low speed temp for the electric fan.

    There is plenty of coolant in the car. I get a steady stream of coolant from the bleed screw, and there are no more bubble showing up in the reservoir.

    The temp gage stays just below 1/2 most of the time, but sometimes is slightly lower. It does not go below 1/4, even at speed on the interstate, once warmed up.

    The hoses from the thermostat housing area and the head to the firewall are good. I've disconnected them at the firewall, and hot coolant is available there.

    I've seen that the heater valve can be an issue, but if it is stuck open, you have heat all the time and the default condition is open. I unplugged the electrical connection at the top of the valve. With the temp control all the way to hot, there's no voltage to the valve. If I turn the knob to cold, I get voltage at the valve. So that appears to be okay. In addition, I can feel movement in there while moving the knob from hot to cold.

    Flapper valve is working. You can hear it 'thunk' closed when you move the knob.

    While I was looking under the dash at the valve and etc., I did see a sensor of some sort hanging loose. It is metallic, about two inches long, small diameter, and curved. The end is blunt. There's a hole in a plastic part near the heater valve that this goes in. What is this piece, and how should it be oriented for reinsertion? Some posts mention a thermostat in the center console. Could this be associated, and if this isn't working, could that be the cause of no heat?

    Finally, could the heater core itself be the root cause of no heat?

    I know its almost spring, but the key word is almost. I need heat!! The alternative is to drive my Ford truck every day - low speed, low gas mileage, etc.

    TIA for your help on this one.
    Last edited by cochran; 02-24-2007, 08:09 PM. Reason: Missing info
    Cochran
    '88 325iC - daily driver, work in progress

    #2
    bump

    I'm troubleshooting this exact issue this weekend as well.

    Comment


      #3
      any update on this? i have the same problem

      Comment


        #4
        A lack of heat when everything else appears to be working can be due to an air bubble in the heater core. Proper bleeding (procedure below) will cure that. But is it possible that one can have a blockage in the core or valves that aren't opening. The diagnostic for that is to disconnect one of the heater hoses and connect it to a source of low pressure water and see if you can get flow that way.

        1) Using ramps or a jack get the front of the car 1' or more higher than
        the rear. That will make the radiator and bleed screw the highest point
        on the engine and facilitate removal of air.

        2) With the bleed screw open, add coolant until no more air comes out of
        the bleed.

        3) Leave the filler cap off, or at least loose, and set the heat for max
        temp and fan speed. Leaving the cap loose will prevent air that's still
        in the system from causing a "coolant fountain" once the engine heats
        up. Start the engine and allow it to warm up to operating temp. As it
        warms up occasionally crack the bleed screw to release any air and top
        up the coolant as necessary.

        4) Once the engine is at temp bring it up to 2000-2500 for a few seconds
        several times. Then crack the bleed until no more air is released. At
        this point the heater should be throwing lots of hot air, which
        indicates that the heater core is filled with coolant. You may have to
        repeat this a few times to get all the air out.

        5) Drive the car a bit, allow it to cool back down, and recheck the
        bleed for air. Over the next few days you may get very small amounts (a
        few bubbles) of air out of the bleed screw.
        The car makes it possible, but the driver makes it happen.
        Jim Levie, Huntsville, AL

        Comment

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