Servicing AC unit

Strecker25

Well-Known Member
SILVER Sponsor
Nov 20, 2014
4,905
Rochester, NY
Boat Info
2002 410DA
Engines
Caterpillar 350HP 3126
On our 290 I have what I would assume is the original 10k btu AC/Heat unit. It works ok, but it's very loud. The design isn't great because the intake is under the stairs so it fires at the vberth directly but it's loud enough to wake us up when it turns on. The noise is the compressor, we leave the fan going on low while we sleep.

Is it worth having it looked at for a possible recharge? I know if the freon is low there may be a leak that we should diagnose, but I was thinking we could stretch the service life for a bit with a fresh fill if it turned out to be low.

The alternative obviously is to replace it, but a 10k btu unit isn't cheap so I'd like to avoid it if possible.
 
Checking the level of freon in the system is fairly straightforward if you can access the unit and can see the charge ports. Most systems have two ports, one low pressure, and one high pressure. On the unit will be a tag indicating what type of freon to use in the system. A stop at the local auto supply and you can purchase your own re-charging kit that comes with a pressure gauge and instructions. The air temp should be above 65 degrees F (I think, read instructions) to charge. Without the proper amount of freon, the compressor will rattle like a golf ball in a can. The freon carries the oil through the system, so keeping a proper charge is important. This will also help your heating cycle if you use it.

https://www.amazon.com/Ultra-Synthe...3&keywords=auto+air+conditioning+recharge+kit
 
Report back on what you find out.

I truly don't find mine too loud.

It's very similar to the amount of noise the HVAC system made in my previous 2011 260 DA.
 
If you decide against a professional taking a look, please DO NOT add any refrigerant without first gathering some data points on the unit and operating conditions. Take temperature readings
(with a good thermometer)
on the inlet and output ends of the unit (air going in and air coming out). Also get some pressure readings, especially on the low side, as well as the ambient temperature at the time of the readings. Also confirm that your unit is using R22 - should be on the metal plate attached to the unit.
These data points will help with providing you more information on next steps. You might also post a video of the unit running so that we can sort of get a sense of the compressor's noise level. These compressors are LOUD especially in small quarters. If the unit is cooling effectively, you might just need to look into some additional noise insulation around the compressor.
 
Thanks guys, I'll get a good video. I've listened to neighbors units (one on another 98 and another on a 2007) without their covers in place and ours is definitely louder, but it doesn't sound like rattling it's just loud. On startup it's loud enough to wake us both our of a deep sleep, so we've had to build pillow forts in front of it (leaving enough room for air to get to the intake)
 
Thanks guys, I'll get a good video. I've listened to neighbors units (one on another 98 and another on a 2007) without their covers in place and ours is definitely louder, but it doesn't sound like rattling it's just loud. On startup it's loud enough to wake us both our of a deep sleep, so we've had to build pillow forts in front of it (leaving enough room for air to get to the intake)

On closer inspection I wonder if there's some rubber isolaters that need to be replaced that would help combat the noise from the vibration of the compressor.
 
Here's the video, not sure how much justice it will do but you can hear it turn on and that the compressor is significantly louder than the fan

I got LO PS for the first time today while in heating mode, but the water is like 42* so it's pretty close to minimum operating temp. Water flow is excellent, strainer clean.

 
Sounds relatively normal to me, especially for an older unit. If it was low, it would cycle on and off a lot. Compressor might just be getting a little tired.
 
Sounds relatively normal to me, especially for an older unit. If it was low, it would cycle on and off a lot. Compressor might just be getting a little tired.

It actually does cycle quite a bit, especially when turning it on for the first time that day. If it runs for 60 minutes in cool mode I'd guess it cycles every 5-10 minutes.
 
Sounds very similar to mine.

Next time I'm at the boat I'll do a similar video.

BTW what kind of filter material are you using behind the inlet vent?

Have you done a factory reset lately?
 
Sounds very similar to mine.

Next time I'm at the boat I'll do a similar video.

BTW what kind of filter material are you using behind the inlet vent?
There's nothing there, I just clean it a bunch. I think it's supposed to have the slide in filter type. you?

Have you done a factory reset lately?

Yeah, last year I did a few times. The display goes wonky and the reset fixed it

Maybe it is just tired. I'm extra sensitive to it this year because we'll be sticking our newborn down there to sleep but maybe the buzz will drown out all the dock parties ;)
 
Right now I have a metal filter that I vacuum from time to time but I did pick up some white nylon "cut to fit" filter material from Home Depot that I'm going to use this year.

https://www.homedepot.com/p/True-Bl...r-Return-FPR-1-Filter-Pad-CAR1030-1/202446748

Without a filter I bet your condenser could use a good cleaning.

Have you removed the wall in the berth to take a look?

It's a PITA to get to and seems like they put the HVAC in backwards to me but I guess they had to do it to get the fan orientation correct.
 
maybe put some sound deadening material on the walls around the unit as well on the front access panel.....

cliff
 
Right now I have a metal filter that I vacuum from time to time but I did pick up some white nylon "cut to fit" filter material from Home Depot that I'm going to use this year.

https://www.homedepot.com/p/True-Bl...r-Return-FPR-1-Filter-Pad-CAR1030-1/202446748

Without a filter I bet your condenser could use a good cleaning.

Have you removed the wall in the berth to take a look?

It's a PITA to get to and seems like they put the HVAC in backwards to me but I guess they had to do it to get the fan orientation correct.

Yeah I have it off right now actually so I could get to the unit. It is a ridiculous design because of that vent hose you can't easily just remove the panel from the aft cabin.
 
maybe put some sound deadening material on the walls around the unit as well on the front access panel.....

cliff

Yeah, probably the best place to start. The "pillow in front" method makes it bearable so a more permanent solution would be nice. Just have to be careful of limiting return air, that's where it pulls from
 
We replaced one of our units, Cruisair, Pretty easy swap. Not really happy with it, It will stop cooling, and will not start back cooling till you press cool on the controller. Been on the phone with them and they say they are temperamental around 72 degrees. There answer to the fix was run it at a lower temp setting or higher setting by 6 or 7 degrees, REALLY !! What a fix to a problem.
 
We replaced one of our units, Cruisair, Pretty easy swap. Not really happy with it, It will stop cooling, and will not start back cooling till you press cool on the controller. Been on the phone with them and they say they are temperamental around 72 degrees. There answer to the fix was run it at a lower temp setting or higher setting by 6 or 7 degrees, REALLY !! What a fix to a problem.

that's crazy, I'm sure it wasn't cheap. I was looking at the MarineAire but then reviews say they're cheap made in china units.
 
Have you ever removed the unit to clean the coil. If not after all theses years it is probably pretty nasty. When the coil is dirty it increases pressures and compressors get noisier. If you decide to replace, look in Mermaid Marine Air, they are in Ft Myers Fl. and are made there. We have 3 Mermaid units on our boat, they have run 24/7 for 10 plus years. Sometimes I can't tell if the compressors are running. If you go that route, order the upgrade digital controls.
 
Curisair does sell a sound shield that fits over the compressor. Not sure if their retrofit kit fits all models though. I installed the sound shield on one of my two units on a 2005 390DA and noticed quite a drop in noise. I found noise to be more prominent while in 'heat' mode versus 'cool' mode. In any event, the sound shield helped however, I'm not sure what the longer term effect of the sound shield would have been on the compressor life because it does inhibit some cooling of the compressor.

Tom
 

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