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  1. #1
    Join Date
    Nov 2009
    Posts
    16

    scroll compressor loud noise for defrost

    Background:
    The unit is an armstrong 17 seer less then a year old. Worked great all summer but as soon as we went to heat we would hear a loud humming noise from the outdoor unit when it started up and went into defrost. The installer came back out and initially thought the compressor was bad so he replaced it but it still made the same noise. After more research he found there is a delay jumber on the deforst board that is suppose to stop the compressor for 30 seconds when going in and out of defrost. He took the jumper out but it still makes the same noise.

    I also tried placing the unit and cool and it made the same noise for a long time. It seems like whenever it switches between hot and cold eaither deforst or not it makes this noise. When it does into deforst i can hear the reversing valve go and the loud swoosh then the compressor makes the loud humming noise for like 10 to 30 seconds.

    Right now the installer thinks there is a problem with the delay because it doesnt seem like the compressor is turning off. When it goes into deforst the fan is still spinning but he never seen this problem before and isnt really sure if thats the issue. I wanted to see what everyone here thought about it.

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,901
    The delays do help but still, in & out of defrost can be noisy switching refrigerant flow, maybe some liquid entering the compressor briefly.

    Sis's inlaws live in an all electric neighborhood full of cheapo Lennoxes. Talk about noisy. Can here the defrosts from blocks away. They called me over to hear a noise, finally triggered a defrost and they said that was what they heard.

  3. #3
    Join Date
    Nov 2009
    Posts
    16
    It seems to always make the noise on initial startup in heat also. Does it switch the flow when it starts in heat mode every time or is this something else happening in the compressor.

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,901
    Again, not totally unusual. A little liquid may be migrating to the compressor during the off cycle. More common if the indoor unit is above the outdoor unit but can happen regardless. Was at a customer's house the other day and his does it. Refrigerant level is fine. No ideas.

  5. #5
    Join Date
    Nov 2009
    Posts
    16
    thanks for replying. The indoor and outdoor unit are about the same ground level but the refrigerant line comes in the house runs up to the celing then back down. Also it never made the noise starting when we were running cool mode before the first heat run.

  6. #6
    Join Date
    Sep 2000
    Location
    Granite City IL USA
    Posts
    765
    Quote Originally Posted by joe55555 View Post
    Background:
    The unit is an armstrong 17 seer less then a year old. Worked great all summer but as soon as we went to heat we would hear a loud humming noise from the outdoor unit when it started up and went into defrost. The installer came back out and initially thought the compressor was bad so he replaced it but it still made the same noise. After more research he found there is a delay jumber on the deforst board that is suppose to stop the compressor for 30 seconds when going in and out of defrost. He took the jumper out but it still makes the same noise.

    I also tried placing the unit and cool and it made the same noise for a long time. It seems like whenever it switches between hot and cold eaither deforst or not it makes this noise. When it does into deforst i can hear the reversing valve go and the loud swoosh then the compressor makes the loud humming noise for like 10 to 30 seconds.

    Right now the installer thinks there is a problem with the delay because it doesnt seem like the compressor is turning off. When it goes into deforst the fan is still spinning but he never seen this problem before and isnt really sure if thats the issue. I wanted to see what everyone here thought about it.
    The compressor turning of should be really easy to determine by sound but compressor amps is a dead give away. It's probably related to the reversing valve moving slow the delay should solve it. There are other checks but the tech would be needed to explain.

  7. #7
    Join Date
    Nov 2009
    Posts
    16
    the tech is in contact with armstrong and i think they are going to replace the whole unit. I hope that solves it.

  8. #8
    I would be amazed if you got a whole new unit. See if it has a crankcase heater on it. This will help. At 17 Seer, I would hope it does. As far as the noise, it is somewhat normal, check the unit specs to see the decibel ratings. Carrier utilizes the "Quiet Shift Defrost" and my customers really like it. Try standing next to a 10 seer Goodman from the late 90's during defrost, sounds like a grenade just went off. I was working on an apartment complex one time, and 6 were right next to each other and surrounded by a brick partition, it made me grab my tool bag and roll out.

  9. #9
    Join Date
    Mar 2009
    Location
    Golden, Texas
    Posts
    20
    Checking the amp reading would be helpful when the compressor was humming. I could determine if the compressor was under a load. The humming noise could also be the reversing valve not operating correctly.

  10. #10
    Join Date
    Oct 2004
    Location
    Harrisburg, Pa
    Posts
    56

    This noise problem may get nasty!!!

    I recently installed an Armstrong 18 SEER HP. It ran great in the cooling mode. When the first cold weather arrived my customer called to say the outdoor unit was making a buzzing sound and her house was cold. My first thought was the unit was in defrost and maybe I made an error in wiring, hence the Aux Heat did not come on during defrost. The customer said the unit was doing this for more then one hour. I instructed the customer to shut the outdoor unit off at the breaker and await my arrival. When I got there I found the comprssor to be pulling lock rotor amps and the diagnostic board showing a fault code indicating a voltage issue or a capacitor failure. The capacitor checked out fine as did the voltage. Refrigerant levels were not out of line. Allied Air Tech Support suggested a hard start assist kit be installed. I tried that and the unit started.(maybe with a little struggle, but it started) It ran well . I took it in and out of defrost a few times and all seemed well. A few days later I got the same call from the customer with the same issue. Allied Tech Support suggested I change the defrost board.
    I did that and had the same issue again. Allied Air Tech Support canot give me a workable solution.
    My last trip back netted the compressor pulling lock rotor amps period.

    I talked with a field rep. for a large wholesaler who was very familar with this issue. He told me it was a hit or miss thing. No real solve available.
    Good is all he said to me.
    Keep a careful watch on your equipment and work closely with your service person on this issue.

  11. #11
    Join Date
    Sep 2000
    Location
    Granite City IL USA
    Posts
    765
    Quote Originally Posted by threadcutter View Post
    I recently installed an Armstrong 18 SEER HP. It ran great in the cooling mode. When the first cold weather arrived my customer called to say the outdoor unit was making a buzzing sound and her house was cold. My first thought was the unit was in defrost and maybe I made an error in wiring, hence the Aux Heat did not come on during defrost. The customer said the unit was doing this for more then one hour. I instructed the customer to shut the outdoor unit off at the breaker and await my arrival. When I got there I found the comprssor to be pulling lock rotor amps and the diagnostic board showing a fault code indicating a voltage issue or a capacitor failure. The capacitor checked out fine as did the voltage. Refrigerant levels were not out of line. Allied Air Tech Support suggested a hard start assist kit be installed. I tried that and the unit started.(maybe with a little struggle, but it started) It ran well . I took it in and out of defrost a few times and all seemed well. A few days later I got the same call from the customer with the same issue. Allied Tech Support suggested I change the defrost board.
    I did that and had the same issue again. Allied Air Tech Support canot give me a workable solution.
    My last trip back netted the compressor pulling lock rotor amps period.

    I talked with a field rep. for a large wholesaler who was very familar with this issue. He told me it was a hit or miss thing. No real solve available.
    Good is all he said to me.
    Keep a careful watch on your equipment and work closely with your service person on this issue.
    The compressor pulls lock rotor continuous?
    If the noise sound like a jack hammer (loud and pulsing) it's the reversing valve getting stuck somewhere in the middle.

  12. #12
    Join Date
    Sep 2007
    Location
    NC Coast
    Posts
    2,604
    Quote Originally Posted by simplyrollin View Post
    I would be amazed if you got a whole new unit. See if it has a crankcase heater on it. This will help. At 17 Seer, I would hope it does. As far as the noise, it is somewhat normal, check the unit specs to see the decibel ratings. Carrier utilizes the "Quiet Shift Defrost" and my customers really like it. Try standing next to a 10 seer Goodman from the late 90's during defrost, sounds like a grenade just went off. I was working on an apartment complex one time, and 6 were right next to each other and surrounded by a brick partition, it made me grab my tool bag and roll out.
    Yes check for a crankcase heater. I too would be surprised if you got a whole new unit. Especially if you just got a new compressor.
    The sound normally comes from when the compressor gets loaded up and there is some liquid getting to the compressor. It could be over charged.
    Silent Service........ Death From Below!

    Somewhere in Kansas, a town found a village idiot!

  13. #13
    Join Date
    Nov 2009
    Posts
    16
    Update:
    The installer now thinks it might be a bad txv valve and the distrupitor has agreed to supply a whole new outside unit to replace mine. They are going to schedule next week to replace it.

    The sound does kinda sound like a jack hammer and i tried regular heat yesterday and the noise lasted for over 2 minutes until i shut the unit off. This was when it was like 65 outside so it lasted alot longer then defrost if it was in defrost. I think the new compressor they put in is already bad.



    Threadcutter, thank you for your reply that sounds exactly like my problem. will the new outside unit fix my problem? Is it a hit or miss with the equipment coming from armstrong?

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