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Thread: A/C compressor pulley frozen up - Advice?

  1. #1
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    Arrow A/C compressor pulley frozen up - Advice?

    Hi,

    The compressor pulley on my 93 ZJ just froze up on it's shaft so the fan belt won't turn. The compressor part seems to turn OK however.

    Any advice on replacing the pulley? Anything I should look out for? Should I swap the clutch too? Everything got very hot from the belt friction over the stuck pulley.

    When I bought the car last year the owner said the A/C didn't work, but just a week ago i put some freon (134a) in it and it was working great--so maybe there had just been a small leak? Any ideas on why the pulley would croak right after I re-filled the system?

    Thanks for your advice!

    Art
    Great 93 ZJ 5-speed! Borla, K/N with Rusty's Airtube, Manik, etc.

  2. #2
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    There's a high possiblity that the oil in the system is low and with no lube in the compressor the pistons and every else inside simply seized up. If the pulley turns freely when the a/c is off and stops when a/c is on then its the compressor that needs replacing.
    1994 Hunter Green ZJ, 5.2L(Retired)
    2006 Commander Steel Blue Metallic 4.7 V8

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    Hi Armax,

    Thanks for the advice. I figure there may be enough oil as the cans I added each had 2 or so ounces of oil--it said on the can it was the correct amount, but I should check the factory manual.

    The pulley is just totally frozen, clutch on or off. The inner part--the compressor does turn so the compressor is not frozen up itself. I wonder though if the heat from when the it froze up and the belt created a lot of friction heat could have damaged the compressor though. Any thoughts?

    Thanks again,

    Art
    Great 93 ZJ 5-speed! Borla, K/N with Rusty's Airtube, Manik, etc.

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    I think the inner part free wheels until the clutch is engaged which connects the inner part to the outer part. The outer part is what drives the compressor. I am not a hundered percent but I think the part that is in contact with the belt has to free wheel. It is probably the compressor froze up. If you put the refrigerant in did you make sure the high pressure side was within its safe limits? The kits the stores give you do not even have a guage for the high side. Just some suggestions.
    2000 Laredo stock for now.

  5. #5

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    -=- originally posted by ArtH -=-
    Hi Armax,

    Thanks for the advice. I figure there may be enough oil as the cans I added each had 2 or so ounces of oil--it said on the can it was the correct amount, but I should check the factory manual.

    The pulley is just totally frozen, clutch on or off. The inner part--the compressor does turn so the compressor is not frozen up itself. I wonder though if the heat from when the it froze up and the belt created a lot of friction heat could have damaged the compressor though. Any thoughts?

    Thanks again,

    Art

    Did the can say "ester oil"? I've ssen many of those cans with 2ounces of ester oil at various auot parts stores.

    Unfortunately, that's the wrong kind of oil for our systems. Our systems use ND8-PAG oil. I've never seen R134a cans preloaded with it.

    I'm not sure I understand the problem (hey, it's been a tough week) ...

    if the pully is "frozen" what happens when the engine is on? Belt just sliding past making all kinds of ugly noise? Or is the pully turning and something else is frozen?
    like my name says:
    97 ZJ - it's green ... OME lift, various JKS goodies, Kolak ignition

  6. #6

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    Oh, and our systems hold 7.75 ounces of ND-8 PAG oil. If you aren't replacing any parts, you shouldn't need to add oil regularly. If you have a leak, the FSM instructs you to add 1 ounce after replacing the leaking part. (Remember, most of the oil resides in the accumulator, condensor, and evaporator ... all of which supply a very very light circulating oil "mist" (the best way I know how to describe it) in the R134a flow.

    Since many people choose not to replace things like a slowly leaking evaporator, but rather add R134a on occasion ... a reasonable approach is to add 1 ounce of ND-8 PAG oil every 3rd or 4th can of R134a. Remember, too much oil is bad too since it reduces system efficiency.

    Total R134a capacity is 1.75 pounds. That's about 2 and 1/3 of those 12 ounce cans. If you end up adding more than a can and a half at any given time ... there's a good chance air has entered the system and you'll need to do a fully evacuation and recharge.
    like my name says:
    97 ZJ - it's green ... OME lift, various JKS goodies, Kolak ignition

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    Hmmm. The cans I used say Ester oil, "retains less moisture than PAG".

    Should I add some PAG too? do they co-exist well? I guess they must or that kit would cause all sorts of complaints for the company-- Interdynamics I think.

    Yes, with the pulley locked, the belt was howling and shrieking at it was forced around the stuck pulley. The compressor part of the clutch turns just fine.

    I think the previous owner took the Jeep to a shop that detected a leak, and since he didn't have them fix it, they "helped" by depressuring the system (or it simply leaked to atmosphere pressure but that seems less likely as it held pressure fine for the week I had it going). I depressed the low pressure port and got no excaping gas at all. No rush of air into an evacuated system either.

    Question: if the shop just depressurized the system, would most of the original oil have rushed out or would most of it stay?

    I added 2 14oz cans-12oz/134a+2oz oil. the first can got it so the low pressure liquid line got frost on it, and with the 2nd can the system worked just fantastic--cold air out the vents, and as per the service manual, the in and out of the evaporator temps were similar.

    Anyway, this weekend I'm putting in a replacement pulley assembly and hope she works fine. I had noticed a wobble to the pulley before it failed so maybe that's all it was.

    Any way to know if there is air and moisture in the system, other than less cooling efficiency?

    Kind of a rambling note. Thanks for your help everyone!

    Art
    Great 93 ZJ 5-speed! Borla, K/N with Rusty's Airtube, Manik, etc.

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    Well I solved one part of this: I took off the pulley and clutch (very easy, don't have to remove compressor or even fan shroud)

    The bearings on the pulley seem fine. It was a bad clutch coil that melted to to the pulley, so when I stopped the car it stuck like glue the pulley to the coil.

    So that's why.

    But fellow Jeepers, a few questions of advice would still be helpful:

    1. Why could the clutch have croaked--obviously it got real hot. Could it be oil leakage?--there was evidence of a bit of oil from the compressor shaft. Old age? Compressor running too hot?

    2. Am I pretty safe just putting in a new clutch assembly?

    3. Please read my immediate previous posting on this subject, where I ask a few other questions about oil, etc.

    Thanks!

    Art
    Great 93 ZJ 5-speed! Borla, K/N with Rusty's Airtube, Manik, etc.

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