Community Forums

YC1 · 12-05-2017, 07:05 AM

I have worked on many modifications over almost 5 years to quiet mine down.

The quick air release section on my grills was a huge source of noise.

The intake area is the other major source.

I have built many mufflers and tried to invent a universal model but have failed so far. However my current model works well enough that I don't have to chase the tv up and down as it cycles on and off.

The basic concept is to block the exit of the plastic cover and make sure the ceiling vents are installed for optimum air flow.

Then the input air is redirected from the vertical area to one section to opposite of where we sit most of the time.

lostinfla · 12-06-2017, 05:50 AM

Newmars don't have the big grill with the "quick air release". They are fully ducted, but I remember a former coach that would drive you out from the AC noise if you opened the main air outlet.
Bill, I had heard it was something to do with fan speed. Not sure if the DS has more insulation in the roof which would make a difference too. On the Baystar, I was also told that some of the units were tightened down too much thereby collapsing the isolators. I did pull the lag bolts (4) that mount the unit, re-silicone them, and reinstall (not as tight) which seemed to help.

bruceisla · 12-06-2017, 06:05 AM

Quote:

Originally Posted by lostinfla

Newmars don't have the big grill with the "quick air release". They are fully ducted.
Bill, I had heard it was something to do with fan speed. Not sure if the DS has more insulation in the roof which would make a difference too. On the Baystar, I was also told that some of the units were tightened down too much thereby collapsing the isolators. I did pull the lag bolts (4) that mount the unit, re-silicone them, and reinstall (not as tight) which seemed to help.

It can be difficult to determine the source of the noise. In general, since Newmar/Dometic units are bolted from the top with lag bolts, the Dometic torque spec is meaningless. Mostly it's trial and error to get the units bolted evenly without twisting the A/C lower frame/pan.

lostinfla · 12-06-2017, 06:38 AM

Forgot to add, the noisier one of the two on the Baystar (rear) had been replaced by North Trail, so I assume they tightened it too much. As mentioned earlier, I also noticed the copper lines in the unit vibrated and caused some noise. Maybe some armor flex (air conditioning suction line foam insulation) would help dampen it.

YC1 · 12-06-2017, 07:54 AM

If you notice the tall walls along highways you can get the idea of how to redirect or block the noise.

The noise coming from the intake area is huge so blocking that noise from coming straight down and bouncing off the floor was my goal.

I had a pool pump that bugged me so built a rock wall around it and the noise level drop was amazing.

Experimenting with how big of an opening to use and how to build something that was serviceable took many hours and years.

bruceisla · 12-06-2017, 04:13 PM

Quote:

Originally Posted by YC1

If you notice the tall walls along highways you can get the idea of how to redirect or block the noise.

The noise coming from the intake area is huge so blocking that noise from coming straight down and bouncing off the floor was my goal.

I had a pool pump that bugged me so built a rock wall around it and the noise level drop was amazing.

Experimenting with how big of an opening to use and how to build something that was serviceable took many hours and years.

Newmar uses a different air distribution system. Staggered round ports running slightly off center from front to rear. Depending on vehicle length, about 12 intake and 12 exhaust. There is no intake or exhaust directly under an A/C. I'm sitting in the living room and counting 5 intake and 5 exhaust between the windshield and mid-hall.

harleyjt · 12-06-2017, 04:23 PM

Maybe I'm lucky but the Penguin HPs on my Kountry Star are very quiet.

bruceisla · 12-06-2017, 06:14 PM

Quote:

Originally Posted by harleyjt

Maybe I'm lucky but the Penguin HPs on my Kountry Star are very quiet.

If they are original they are likely DuoTherm or Penguin series 1 (not II) units.

"007" · 12-06-2017, 06:25 PM

Quote:

Originally Posted by harleyjt

Maybe I'm lucky but the Penguin HPs on my Kountry Star are very quiet.

The old coach's never had these problems.
One year the AC's put on coach's were all noisey from AC MFG and a batch had to be replaced.
Others changed their AC and didn't use prober seals or tighten to tight and all vibrations traveled through the whole roof area.
There should be a installation booklet with AC for installation.
QT's 1 & 2 have all AC install information.

harleyjt · 12-06-2017, 11:41 PM

Quote:

Originally Posted by bruceisla

If they are original they are likely DuoTherm or Penguin series 1 (not II) units.

Correct - Penguin 1 series.
jt

bruceisla · 12-07-2017, 04:43 AM

Quote:

Originally Posted by harleyjt

Correct - Penguin 1 series.
jt

Ah...the units that worked for a few years

bruceisla · 12-07-2017, 05:30 AM

Quote:

Originally Posted by 007";3932844]The old coach's never had these problems.
One year the AC's put on coach's were all noisey from AC MFG and a batch had to be replaced.
Others changed their AC and didn't use prober seals or tighten to tight and all vibrations traveled through the whole roof area.
There should be a installation booklet with AC for installation.
[B][URL="http://www.irv2.com/forums/f103/original-part-1-and-2-quick-tips-and-easy-mods-18509.html

QT's 1 & 2[/URL][/B] have all AC install information.

The Dometic installation manual is quite good for conventional (bottom bolted) units .... not so good for a Newmar.

On a conventional install the unit is bolted from the bottom thru a square plate that sandwiches the inside vinyl trim, insulation, roofing material, rubber gasket, and bottom A/C frame (pan) ... nothing in contact with the metal RV frame.

On a Newmar, the unit is bolted from the top. Four steel lag bolts go thru the A/C bottom frame and into a square metal frame that is welded to the RV frame under the roofing material. The lag bolts (metal) pick up the vibration from the A/C and transmit it to RV frame. It's critical to not overtighten the A/C. Torque specs are worthless due to the use of lag bolts. Compression of the gasket by 1/4" or so is all that is necessary. A fender washer and rubber gasket between the lag bolt and A/C pan helps deaden the sound transmission. A properly tightened unit will have the corner rubber blocks in contact with the roof but not compressed and, if you lift the pan at the corner, the rubber blocks must still contact the roof. Tighten each bolt in an incremental pattern like you were mounting a tire/wheel. Don't put a twist in the pan !! A big blob of silicone sealer between the bolt head and pan keeps the bolt from backing out.

Check the installation annually. Bolts can be retightened slightly but over time the big gasket will compress from the weight of the A/C and should be replaced. The A/C unit should not be continuously retightened.

BTW, if the tech is not familiar with a Newmar I can almost guarantee this will get screwed up ....

Finance · 01-06-2018, 09:14 AM

I agree with the reply above, in our Baystar the noise issue was the compressor vibration transmitted throughout the metal roof structure. Sort of a low droning noise which became more irritating over time. I don't really know if it became worse or we just became more observant. Definitely more noticeable when running the heat pumps too. We eventually resorted to running the heat pumps prior to sleeping and switching to the furnace when we went to bed.

Jn1edosp · 01-07-2018, 01:40 PM

Thanks everyone for your feedback. My front AC unit died over the Christmas holiday while we were visiting relatives in Naples. My inverted died in an unrelated death (separate thread) so the dealer is in the process of ordering replacements for each. I am working with Dometic to upgrade the AC unit from 13,500 BTU to 15,000 BTU assuming the profiles are the same because I don't want to add height to the RV.