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  1. #1

    Fan making odd noise and pulling current when off

    I've got a Rheem air handler that has just recently started making a odd hissing/screaming noise. It's not real bad, but bad enough that I have quit running it until I find the problem. I have a wood burning furnace that is tied into my ductwork and when the blower kicks on with it, I have the air handler wired to come on too. There is also a bypass humidifier tied into the system that runs when the humidistat calls and has a current sensing relay to make sure the air handler fan is running before it turns the solenoid on.

    So I turned off the air handler fan on the thermostat controller and the humidifier solenoid kept running. So my first thought was it was just a coincidence and the solenoid was bad. Well I flipped the breaker on the air handler off and the solenoid clicked off too (they are on different circuits). So that means the current sensing relay was keeping the solenoid open which means that the fan motor was still drawing power.

    Now I'm to the point where it's over my head. I thought it may have something to do with a capacitor but I don't know. This system has been working just fine for about 3 years with this setup. Any and all help would be greatly appreciated.

  2. #2
    Join Date
    Nov 2004
    Location
    Austin, TX
    Posts
    887
    I'd call a service tech. Two different symptoms that may or may not be related. The screeching sound is bad.. Power flowing through that sensing relay when the blower is shutoff is bad. The technician should be able to figure out where the power is flowing from and find out the source of the hissing/screaming noise without electrocuting himself. Unlike 120 volt AC, 230 volt AC is not a power line and a neutral. BOTH lines are hot and out of phase with each other.
    I am for doing good to the poor, but...I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it. I observed...that the more public provisions were made for the poor, the less they provided for themselves, and of course became poorer. And, on the contrary, the less was done for them, the more they did for themselves, and became richer.
    ― Benjamin Franklin

  3. #3
    My father in law came over a couple of days ago (he does hvac stuff for a living). We changed out the motor, the bearings were bad on it and the fan was kinda wobbly. So I figured that would solve the problem. Well after hooking it back up it still makes the same sound. It's not longer keeping the current sensing relay on though so that part of the problem is solved.

    It's really more of a loud rattling sounds like the fan is scrubbing something but it turns just as free as it can when we take it out and spin by hand. We took out the heat strips to make sure something wasn't loose in them causing the noise and that wasn't the problem. We've checked everything, every screw to make sure it was tight. We just can't find any reason that it would be making the noise. Any other ideas?

  4. #4
    Join Date
    Feb 2012
    Location
    Toronto Canada
    Posts
    1,090
    Is this belt driven

    What make?
    Model# serial#
    Need more info plz

  5. #5
    Join Date
    Jul 2009
    Location
    Columbia, MD
    Posts
    4,467
    blower wheel out of balance causing it to scrape the housing as it starts up?

    after running, it straightens out and doesnt scrape

  6. #6
    Quote Originally Posted by gravity View Post
    blower wheel out of balance causing it to scrape the housing as it starts up?

    after running, it straightens out and doesnt scrape
    You got it. The wheel had a weight on it to balance that had come off. It was smooth as can be when turning by hand but would rattle when it got up to speed. A new wheel solved the problem and was covered under warranty. Thanks for the reply.

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