240 AC belt jumps off

Discussion in 'Volvo 240' started by flash, Aug 30, 2009.

  1. flash

    flash Guest

    I have a 1993 240 that can't keep the AC belt in the pulleys when
    using the AC. I installed a new belt a month ago when I thought the
    old one had broken (it was just gone!). It worked well with no AC on,
    but it popped off on the way home on a hot day. I reinstalled it,
    making extra sure it had the proper tension, but it jumped off again.
    The AC compressor sounds good and works fine - no indication it is
    seizing up. Has anyone else had this issue, or have any suggestions?
    flash, Aug 30, 2009
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  2. flash

    Tim McNamara Guest

    Check the belt tension and alignment of the A/C compressor pulley.
    There is an adjustment to get it into plane with the main pulley. If
    that is not done correctly, the belt twists and quickly fails or can
    fall off.
    Tim McNamara, Aug 30, 2009
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  3. flash

    James Sweet Guest

    Likely your accessory mount bushings are shot, allowing the pulleys to
    twist out of alignment. Fortunately they're cheap and fairly easy to
    replace with only basic hand tools.
    James Sweet, Sep 1, 2009
  4. I spent some time last night inspecting the AC compressor. The pulley
    is in perfect alignment with the crankshaft pulley. Even with a bar
    pulling on it, I could not detect any movement or deflection of the
    lower mounts where the bushings. This is not a surprise, though,
    because the unit is secured by two bolts on the top, one in the front
    adjustment slot, and another one in the back. I still intend to remove/
    replace the bushings, but I'm doubtful that it will make a difference.
    Kathleen Johnston, Sep 5, 2009
  5. flash

    James Sweet Guest

    Is the harmonic balancer on the crankshaft splitting? Look at the
    pulleys with the engine idling and the AC on, are they both running
    straight and true, or is there a wobble?

    Can't say I've ever had a problem with belts jumping off these.
    James Sweet, Sep 5, 2009
  6. flash

    flash Guest

    Here's an update on what's been done lately.

    Did a complete inspection of the crankshaft and AC pulleys, and they
    are both in excellent condition. No evidence of splitting, warping or
    being out of round. After installing another new belt - a cogged
    Continental - a visual inspection with the engine running showed the
    AC belt and crank pulleys in perfect alignment, with no deflection/
    movement of the AC compressor. BUT - I also saw that the PS belt
    looked funky. The PS belt is driven by the dual groove pulley on the
    front of the AC. Somehow, the PS pump has shifted, so that its input
    pulley was out of alignment both horizontally (as seen when viewed
    from the side) and vertically (as viewed from above).

    The quick and dirty solution was to take three washers, remove a bit
    of each so they could slide over the bottom mounting bolt (which acts
    as a pivot) of the PS pump, and insert them as shims to adjust the
    pump's location. This brought the PS and AC pulleys into near perfect
    alignmant, as viewed from the top. When viewed from side, they are
    close enough for now.

    So far, so good. After a number of test drives, the AC can be used w/o
    losing the belt. My best guess is that when the AC was running and
    under load, once in a while the PS belt would whip a little bit when
    making a turn and just catch the edge of the AC belt, causing it to
    jump off. At least, I hope so - and that this problem is solved.
    flash, Oct 4, 2009
  7. flash

    Randy G. Guest

    It could be that the accessory bushings are worn/loose/shrunk and need
    replacing. The Power steering, alternator, and A/C compressor are all
    mounted on the same type bushing that isolate those components from
    the block. They fit into the lower mounting boss on the part that is
    bolted to the block, and the lower pivot bolts go through them, iirc.
    I found the ones on my Mom's alternator so worn that when we drove it
    home after purchase the alternator pulley had worn the adjustment bolt
    and block over 50% through!
    __ __
    Randy & \ \/ /alerie's
    '90 245 Estate - '93 965 Estate
    "Shelby" & "Kate"
    Randy G., Oct 7, 2009
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