Noice from basement air normal?

[ARNE-T]

The basement airconditioner in our 2006 Adventurer 35A runs quietly for about 5 seconds, then it runs with a very loud low frequency vibration (like a loud hum from a bass speaker) for ten seconds. Then the cycle repeats. The noice is so loud that sleeping is not possible when the AC is running.

Is this normal? If so, I regret having purchased a unit with basement air. If not, what can I do about it.

Arne. Presently at a Walmart in Northern Idahoe

[ARNE-T]

The basement airconditioner in our 2006 Adventurer 35A runs quietly for about 5 seconds, then it runs with a very loud low frequency vibration (like a loud hum from a bass speaker) for ten seconds. Then the cycle repeats. The noice is so loud that sleeping is not possible when the AC is running.

Is this normal? If so, I regret having purchased a unit with basement air. If not, what can I do about it.

Arne. Presently at a Walmart in Northern Idahoe

[smlranger]

When our unit starts it does make the low frequency hum (compressor/s starting up) and there is some vibration. However, it settles down and we've gotten used to it. I would say I am not sure I would go for a basement AC unit next time around.

[MrTransistor]

Hello Arne,
Doesn't seem normal. With ours, once the inside fan is on, we can hardly hear the compressors cycle. When on generator or 30 Amp. shore power, what are the current readings as the compressor cycles? If, during the loud hum periods, the current goes quite high then drops back down when the noise stops, you may have a seizing compressor. Could also be that one of the compressors is short cycling and trying to start under pressure. I suspect it's time for a trip to the service department either way.

Normal running currents on ours are: one compressor = 12 Amps., two compressors = 18 Amps.

[tomsm]

I think what you may be hearing is the noise from the 2 compressors going in and out of "phase", for lack of a better word. When it's doing it, try turning off the circuit breaker for the #2 compressor. If that cures it, you may just want to sleep with #2 turned off, provided #1 can do the job at night. I know it's not very convenient but it may help. I did that a few times, but evenually we just adjusted to the noise and now find it kind of comforting.

[Davel]

Arne-T,
I think tomsm is correct. Our 2004 Adventurer does the same thing. It has been worked on several times with the last time at the 2005 GNR being the most successful. The vendor finally told me that some units go into "phasing" and they have not found out how to stop it. The tech at GNR tightened several panels and it helped, but it is still there. They are going to get another chance this year as well. In the meantime I'm going to try tomsm's suggestion.

Good luck,
Dave

[RKL2]

Could be an harmonic vibration set up by the two compressors running at the same time but at slightly differnt frequencies. .quite common on any dual motors set up and sometimes on drive shafts etc. Usually impossible to make go away. Shouldn't get it when one it running unless small piece of metal is also being impacted by the vibration. RKL

[Tom N]

Check the duct work in the rear cap. Sounds like you have a harmonic vibration in the duct work from the AC unit to the ceiling.