PT air from heater goes from hot to cold to hot.

Discussion in 'PT Cruiser' started by Pete E. Kruzer, Dec 13, 2009.

  1. I notice that the air coming from my heater when set on hot will come
    out cool then back to warm, to cool, and so on.
    The heat gauge is normal. What could be causing this? The PT is a 2001
     
    Pete E. Kruzer, Dec 13, 2009
    #1
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  2. Pete E. Kruzer

    Joe Pfeiffer Guest

    Check the coolant level, especially if it's correlated with engine
    speed. On our Intrepid (I know, completely different vehicle) when the
    radiator tank cracked we learned about it because at low RPMs water
    wasn't getting into the heater core, so the heater went cold at
    stoplights. Temperature gauge read normal.
     
    Joe Pfeiffer, Dec 13, 2009
    #2
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  3. Pete E. Kruzer

    Bill Putney Guest

    I agree with Joe - low coolant/air bubble in coolant. If it has a
    bleeder, open that after the engine is warm and see if any air comes
    out. If so, leave open until only coolant comes out. Check level in
    reservoir and top off if low before and after you bled it. If the
    reservoir is the pressurized type (I don't know about the PT), don't
    open it to add coolant while the engine is warm/hot - let it cool down
    and de-pressurize first.

    If coolant level is OK and no trapped air, the heater core may be clogged.
     
    Bill Putney, Dec 13, 2009
    #3
  4. Pete E. Kruzer

    Bill Putney Guest

    Since you do indicate that you sometimes have some heat, probably ignore
    my last sentence there.
     
    Bill Putney, Dec 13, 2009
    #4
  5. Thanks all!

    I checked the coolant in the radiator. I can not see into the
    resovoir. I added about a quart of 50/50 antifreeze. It bubbled as it
    went into the radiator. I figured this was air being replaced. Seems
    to have solved the problem.
    One more question. I wonder where the missing fluid went. Nothing on
    the engine, under the car. And the oil pan has nothing but oil in it.
     
    Pete E. Kruzer, Dec 14, 2009
    #5
  6. Pete E. Kruzer

    Joe Pfeiffer Guest

    First place I'd look is the easiest: pressure test the system and
    radiator cap (you can borrow a pressure tester from Autozone). If it
    passes that, I'd get worried about the head gasket and related
    problems.
     
    Joe Pfeiffer, Dec 14, 2009
    #6
  7. Pete E. Kruzer

    Bill Putney Guest

    Once again, Joe and I agree - couldn't have said it better. The
    pressure caps have a sneaky way of leaking and not leaving a trace.
     
    Bill Putney, Dec 14, 2009
    #7
  8. Pete E. Kruzer

    sctvguy1 Guest

    Would that also apply to non-pressurized system caps also? My 41
    Chrysler radiator level goes down, but no leaks on the floor or anyplace
    I can see. The cap was new earlier this year, but could it have gone bad?
     
    sctvguy1, Dec 15, 2009
    #8
  9. Pete E. Kruzer

    Bill Putney Guest

    Not sure. The coolant systems back then (10 years before I was born)
    weren't pressurized? The fact that I ask that question shows that I'm
    the wrong guy to ask on that one. :)
     
    Bill Putney, Dec 15, 2009
    #9
  10. Pete E. Kruzer

    Joe Pfeiffer Guest

    Wwhen a pressurized system's cap goes bad it doesn't maintain pressure,
    which results (through a long chain of explanation) in steam escaping
    through it. I've got no experience with non-pressurized systems, but
    I'd assume by definition that you couldn't have the same failure
    mechanism.
     
    Joe Pfeiffer, Dec 15, 2009
    #10
  11. Pete E. Kruzer

    KirkM Guest

    It was probably just low a low coolant level. If the 2.4 in the PT is
    like it is in the cloud cars, the the radiator cap is the highest
    point in the cooling system. The AA cars had a bleeder on the head to
    get the air out. If the system was not bled correctly, it would take
    out the headgasket. I know this from experience.

    I would suggest checking the coolant level on a regular basis. When
    the water pump failed on my cloud car, it would leave puddles of
    coolant on the garage floor. I would also suggest checking the engine
    oil and transmission fluid for coolant contamination. Has the water
    pump and timing belt ever been changed on your PT? It may be time
    since it is a 2001, depending on the mileage. The belt change on cloud
    cars was 101,000 miles.

    KM
     
    KirkM, Dec 16, 2009
    #11
  12. Pete E. Kruzer

    Steve Guest

    Don't know about a '41, but my '49 had a pressurized system. Pressurized
    to a *whopping* 4 psi vs. the ~15psi common today :)
     
    Steve, Dec 16, 2009
    #12
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