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Heat Pump hums, clicks and does not come on sometimes

Lennox Heat Pump- M/N 12hpbz4-4p Excuse me for waiting so long to find solution for problem but I tend to procrastinate. This problem has gone on for a year or so. Cold weather now and the heat pump sometimes makes a loud click when turning on and off. Also, when the air handler comes on inside, the heat pump does not always come on. Instead it makes a loud hum but fan does not switch on.Eventually it does. Twice I went out and shook it and fan came on but i am not sure if it was going to come on anyway and that was just a coincedence. I called Lennox today and to see if I could talk to a tech but could not get past receptionist. She told me that outside unit should come on at same time as inside air handler. Is this true?
Had it serviced last week. Repairman took out indoor coil (which was filthy) and cleaned it outside with solution. Also cleaned outside coils with solution. Heat pump would not make noise of course and fan came on with him here but it was also a warm day if that matters. He turned it on and off a few times. Said he thought it was going to be the contacts, but he said if it was then they would of made noise while he was here and they usually go out for good. He is hinting that it might be motor but when it runs, it sounds great and he did not say anything like it sounded like it was going bad. As mentioned the clicking noise and fan not working while it hums happens often but not all the time. Not sure if I am imagining that it happens more in colder and warmer weather or just happens that I am outside and happen to hear it.

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  • gulfbeach47 Jan 08, 2009

    I am guessing that the start capasitor is what is stopping the fan from coming on?

    Contactor chattering? Did you mean the contractor (technician) or is that a part? If it is the part, would that be what's making the loud clcik at times when heat pump come on and shuts off?

    Also, was the lady correct at Lennox when she said outside unit should come on at same time as indoor handler?

  • gulfbeach47 Jan 08, 2009

    The click or metal ping sound happens when unit comes on and shuts off. When there is a hum, the motor or something in there is making a loud hum but fan blades are not turning. Then there is a sound when fan comes on. Is it just a coincidence that fan comes on when I shake the unit? I can feel the heat coming up from above fans when it is not running. Will the motor burn out when it is making this hum and fan not moving? Can the tech test the start capasitor or do you just switch it out and hope that is the problem?

  • gulfbeach47 Jan 08, 2009

    oops...not sure if last post went through. I pointed mouse over where i was printing and everything vanished. For some reason you cannot copy/paste here.

  • gulfbeach47 Jan 08, 2009

    I guess my other reply went into cyberspace. I hear a ping or metal sounding click when fan comes on and when it shuts off intermittently. Not all the time. Seems like it happens more in colder weather but not 100% sure about that. Happens in heat of summer too. Fan is facing up, so when my air handler comes on and I hear the hum outside, I go out and look and if it is still humming, then the fan is not turning. But at the same time there is noise coming from in the heat pump (maybe the motor humming?) As I look down I feel heat and see steam coming up from unit. I don't feel any heat coming from sides of unit that I have noticed. Don't know about air pressure leaking out sound. It would have to be loud for me to notice because of some hearing loss. Defrost mode? If it has not been running long would it be going into defrost mode? It has been running for a few hours tonight and no hums or click that I have noticed so far. If fan is not turning and unit is humming can motor burn up unless it is defrost mode as you suggest? Is there directions on how to change out a start capacitor some where if that is the problem. And is it hard to get to...especially for someone that has no experience? How much does a start capacitor cost usually?

  • gulfbeach47 Jan 08, 2009

    You wrote> "some brands of units have a delay in the outside units board to stop it from starting at the exact same time as the air handler." Would the brand with the delay sometimes let heat pump start at same time and other times, not let it start for awhile and be humming during this time? Ok. so all tonight it has not made the metal click sound and seems to be running fine, but it will happen again. So, would you be leaning towards replacing start capacitor or ? I forgot to ask last reply is here a way ot test the start capacitor? Kind of unsure what to do about the problem. I hate for the motor to burn up. I am not sure if me technician knew what he was doing. He did not offer any advice. Just $165.00 for cleaning and looking for problem. last time I got the cleaning for $75.00 but it was a friend of a friend.

  • Anonymous Jan 25, 2009

    Steam comes out of the outside unit, and sometimes the fan and green light stays on for a while on the thermostat inside, is this normal?

  • dwkcool May 11, 2010

    sounds like you might have a start capasitor going bad and a contactor chattering


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Yes the start capasitor starts the fan motor and the contactor pulls together when the t-stat tells it to start and it has a spring in it that gets week , some brands of units have a delay in the outside units board to stop it from starting at the exact same time as the airhandler

Posted on Jan 08, 2009

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  • dwkcool Jan 08, 2009

    is this happening when it is very cold out and do you feel the heat from down by the fan area, plus when the fan kicks on does the noise you hear sound like air presure leaking out

  • dwkcool Jan 08, 2009

    if you got my last posted and all of that is true ,the unit is just going into defrost mode and there is nothing wrong with it

  • dwkcool Jan 08, 2009

    if it"s not in defrost mode yes it can burn the motor up and the capasitor can hold anywhere from 370 volts to 440 volts so please be careful around it and they are all different prices

  • dwkcool Jan 09, 2009

    yes I would put a start capasitor on an maybe a hard start kit but for sure a capasitor


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I have a problem with getting my heat pump to come on. Sometimes it will be just fine and other times the green light on the thermostat will just keep blinking...and then at times it will finally come on and about 30secs later shut off without a temp change...Could this be my thermostat going bad??

Posted on Dec 13, 2009

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The pump (compressor) runs in the same direction all of the time. If it has a clicking sound and hum then the motor is not starting. It is then either the starter relay or more likely a start capasitor,if the unit has one .  I hope I have explained well. I also concure that the compreassor shoudl be running when the air handler is on .

Posted on Jan 08, 2009

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