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  1. #14
    Join Date
    Nov 2003
    Location
    Wisconsin
    Posts
    458
    I ended up jumpng up to a 1 hp5.2 amp and it's been fine for acouple of days.Thanx all.
    In my many years I have come to a conclusion that one useless man is a shame, two is a law firm, and three or more is a congress. John Adams

    The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary. H. L. Mencken

    "Life's tough......It's even tougher if you're stupid."
    -John Wayne

  2. #15
    Join Date
    Sep 2002
    Posts
    12,195

    You might be on the right track but I think you may be running the wrong way

    If the motor is not over amping - and the thermal opens - most likely the thermal is defective.

    Forget about the condenser fan blade cooling the motor - it's not a factor.

    Clean the condenser coil to spotless. After that; clean it again. Then run the unit until the condenser coil is dry and check the air temperature increase across it. If it is 10-12-15 - you are moving enough air through the condenser. If the air temperature difference is higher that that - with a Clean condenser coil - you are not moving enough air through the condenser.

    To pick a blade out of the air, so to speak - check the Grainger catalog for blades of the correct diameter. Then pick the one with the greatest pitch which can be driven with 3/4HP. That will give you the largest air flow possible without installing a bigger motor.

    PHM
    -------



    Quote Originally Posted by rango View Post
    Hey Guys and Gals. Working on an old (35) AAON commercial unit. Condenser fan motor .75 hp as per data plate cuts out on thermal after about 45 min.
    Assume bad bearings even though amp draw not changing, install new with cap. Same pattern. Motor draws 5 amps under load which is under plate specs.I'm thinking someone be fore replaced propeller with wrong one and not enough air moving over motor to cool it. Head pressures do seem to be slightly high. Wondering if using 4 blade fan vs. 3 blade and pitch difference, etc. I'm thinking I'd like to increase air flow by 50% or so. Am on the right track?
    Thx
    Rango
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  3. #16
    Join Date
    Dec 2000
    Location
    Flat Rock, NC
    Posts
    463
    Have you checked c rating of motor? Remember supply houses generally carry the least expensive replacement, sleeve bearing or worse motor so they can sell another motor in 2 or 3 years.

  4. #17
    Join Date
    Sep 2002
    Posts
    12,195
    That's not why supply houses carry the cheapest motor. They make a percentage of profit on each sale and so of course would always prefer to sell the Most expensive items - not the least expensive items.

    The reason supply houses carry the cheapest motors is because of all the numb-nuts who will call ten different places for A Price on every little thing and then always buy from the place with the lowest price.

    They call it "keeping them honest" - but what they are actually doing is to ruin their source of supply.

    PHM
    ------






    Quote Originally Posted by codgy View Post
    Have you checked c rating of motor? Remember supply houses generally carry the least expensive replacement, sleeve bearing or worse motor so they can sell another motor in 2 or 3 years.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. #18
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,254
    Quote Originally Posted by Poodle Head Mikey View Post
    That's not why supply houses carry the cheapest motor. They make a percentage of profit on each sale and so of course would always prefer to sell the Most expensive items - not the least expensive items.

    The reason supply houses carry the cheapest motors is because of all the numb-nuts who will call ten different places for A Price on every little thing and then always buy from the place with the lowest price.

    They call it "keeping them honest" - but what they are actually doing is to ruin their source of supply.

    PHM
    ------
    Amen brother. I worked in my families refrigeration wholesale company for 10 years doing everything from cleaning toilets to engineering refrigeration racks. I have seen people walk out, get in their trucks and drive across town for 15 cents and be pissed because I wouldn't come down on the price. And these are supposed to be professionals.

  6. #19
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,590
    OP, did you make any head weigh on your problem? All the AAON units I have ever worked on needed the OEM motor because of the problem you are having. As someone eluded to earlier, it has something to do with the temperature rating. I have ha a couple rodeos with these things and many arguments of why a standard motor won't work.... We ended up putting an OEM motor on and is still running 5 years later.

  7. #20
    Join Date
    Oct 2007
    Location
    Miami, FL.
    Posts
    417
    Quote Originally Posted by ryan1088 View Post
    OP, did you make any head weigh on your problem? All the AAON units I have ever worked on needed the OEM motor because of the problem you are having. As someone eluded to earlier, it has something to do with the temperature rating. I have ha a couple rodeos with these things and many arguments of why a standard motor won't work.... We ended up putting an OEM motor on and is still running 5 years later.
    Bingo !!!
    I miss you mom and dad.

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