What causes this racket?


http://www.youtube.com/watch?v=9gfnmVB5q3c&NR=1

I have a Goodman GSZ (installed Nov) that has started making the same noise during defrost. There is also a neighbor with a Frigidaire that makes a similar noise during defrost. He had an HVAC tech come and tell him that is the way these things work. That was a quick 100 bucks.
I am waiting for a HVAC tech to come but if he also tells me this is "normal" the world will have one less HVAC tech ;)
I paid $540 for commisioning the unit - 3 hours labour. The $40 was for a filter/drier. After checking I've found that there was a drier already installed so this was a waste. BTW, records show 6.6 ounces of R410 was added for tubing but none for extra filter.
The unit ran fairly quiet for about two months until the temp went down to 20F. Should there be a crankcase heater?
Frosting rarely completely covers coils - not much icing on bottom sections. Defrost setting at 30 minutes.
How well do the sound blankets on the compressor work?
Looking forward to the replies - good, bad, funny AND ugly......
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As there were no replies to this, I'll try to answer it myself.
(still awaiting the (new) HVAC tech to come and perform his magic.)
In the meantime, I installed a crankcase heater and sound blanket and found that the accumulator was rattling on startup due to missing nut on mounting bolt. This caused the sounds to be exacerbated.
I think the problem is scroll compressor slugging on foam created by insufficient refrigerant or migration.
Original charge was to be by weight. Factory charge: 35.14 oz Extra line charge: 6 oz
Missing charge for unneeded filter: approx 6 oz
I checked refrigerant charge using the hot gas method (I'm a retired industrial instrumentation tech so this was no big deal) and found a temperature rise of 119 on the hot gas line.
I also ran the unit on a cold, humid day for an extended period and found VERY distinct frost banding on bottoms of coil sections. This unit is at my mother's house so I did not find out about problems till recently so I cannot say when it started. The low refrigerant may also be caused by leak in system. If so, I'll be pretty pissed off if it's in one of the installer's connections!
I called the owner of the original heating/HVAC company and he tried to bullshit me. I should have recorded his dumb comments as he tried to explain the above and say it's "normal". He would not allow me to speak directly to the tech. He wants another $500 to remove the filter and adjust refrigerant. From his comments, I figure he is an old heating dude that got into the HVAC business by hiring an HVAC tech and doesn't know much himself.
I had two quotes for original installation which entailed brazing connecting refrigerant tubing, adding appropriate amount of refrigerant and checking system operation. Electrical and mechanical installation was already done. Unit was running on aux heat and airflow checked using measured line voltage and current of strip heater in conjunction with temp probes. (756 CFM at medium fan speed for 2 Ton unit)
The two quotes were $500 and $350. I took the higher because I wanted a good job done. Go figure....
I have expanded heating data charts (ambient from 65 to -10) for installed split-system to make life easier for tech. BTW, all this information (including fact that filter was already installed) was available for original tech but he just thumbed through it and proceeded to do his job. I trusted him. Now I wonder if he contaminated the system during install.
Will post results from new HVAC tech when he finishes.
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wrote:

Goodman equipment is a half step above Intertherm mobile home junk. Consumer Reports doesn't even rate Goodman because there are so many problems because of internet sales and lowest bidder installs. Did the tech even pull a vacuum on the system before charging? Did he even own a micron gage, let alone how to use it?? or... did he just let the vacuum pump run for 15 or 20 minutes and call it good?? BTW... 30 min defrost cycles waste energy. Demand defrost is preferable.
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wrote:

I went for highest bidder......

Yes - 500 micron.

He had what appeared to be the latest digital equipment including scales. He made good looking joints and used nitrogen. I don't know how experienced he was. He was a young guy.

I left him alone for a good part of the time because I know most techs don't like someone looking over their shoulder all the time while they are working. I simply assumed he knew what he was doing and trusted him to do what was necessary for the commissioning of the unit.

I know. I've now set it to 60 minutes. It is very disappointing to see it go into defrost with completely clear coils.

NOW you tell me ;) Can this be retrofitted with new defrost control and thermostat?
I just wanted a replacement for an old oil guzzler. Remember the cost of oil last year - $147 bbl. I hadn't expected to get this involved in the basics of HVAC. But is has been interesting. Never too old to learn.
Just got a call from HVAC tech - 20 years experience - to tell me he'll come by tomorrow afternoon.
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Steve wrote:

Mow that is amusing. Consumers Report qualifies Goodman equipment by the many names the same unit is manufactured under and each one is scored differently. The same goes for other companies that manufacture the same units under different names. Actually Goodman seems to be as good as the best in longevity. I don't deal in them, but I do repair a lot of very old units. I can name several that don't seem to last that long. Carrier seems to have a shorter lifespan as an example..As does Lennox. Some of the oldest stuff out there is Mueller and Janitrol. Don't forget New Holland and Chicago foundries. You do know of course who makes Sears stuff?

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wrote:

In my search for info on this problem, I came across Amana data sheets - the actual instructions, diagrams and parts list are identical copies of the Goodman ones. They just changed the cover sheets.
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You're becoming a real Einstein there Jean. You think it might have something to do with the fact that Goodman purchased Amana a while back? Me though, if I were looking for Goodman, Id just go to Goodman's site. Bubba
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wrote:
SNIP

Google "heat pump noise defrost cycle" or "heat pump scroll slugging" or whatever. Go 10-20-30 pages deep. I've found sites from ALL suppliers with various problems to do with this noise.
I've already got everything that Goodman produced covering the installed equipment. I just found this detail interesting but not particularly helpful. I could care less who bought who.
BTW, heat pump tech could not check unit until tomorrow because he was running behind. He did stop by for a quick listen because he was passing by. He says unit is slugging during defrost and a bit on startup.
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Jean wrote:

Gee? I wonder why? ;-p
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Here's an interesting comment I found on noise during defrost cycle:
"A scroll type compressor is employed in a heat pump system having a solenoid actuated four way flow reversing valve. A processor monitors a system parameter that is indicative that a flow reversal has taken place or is about to take place, at which time the compressor motor is shut down for a predetermined period of time during which the compressor produces objectionable noise produced by separation of the scroll element due to a low pressure differential over the compressor. At the end of the period, the compressor motor is re energized. The processor is arranged to cycle the compressor at the beginning and end of each defrost cycle or when the system undergoes a change in its operational mode."
The Lennox 34M63 has 30 second compressor delay during switchover as well as 5 minute anti-short cycle. In addition, the high and low pressure lockout feature is preferable to uncontrolled cycling in my mind. The diagnostic LED's are also a nice feature.
Goodman thermostat appears to be close 28F / open 65F from older install book - will have to check current part# B1370803 DEFROST THERMOSTAT
I mentioned this to the HVAC tech and he said it was a good idea. He said he carries these in his truck to use as replacement for defective defrost boards.
Still awaiting his services as he is very busy.
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