'89 Santego, AC problem

[bobwhorn]

The salon unit is not cooling really well. The unit is mounted under the steps coming into the salon, not very accessible. I think I have located the low side pressure connection and have some R410a coming. If that doesn't fix it it will need to be replaced. But How? The steps are carpeted and I can't see any way to remove them. There must be a way, right?
Thanks for any input,
Bob

[km1125]

Did you definitely rule out flow issues on the water side?

[buster53]

I’ll pass this on FWIW…I have a 356, completely different from your boat. However, the steps going down to our aft cabin are also carpeted and I always thought they were not removable. One day, I really started to look at them and I found a couple of screws buried in the carpet. Removed the screws and the entire step assembly lifted out of the way so I could access my starboard transmission, which I was having issues with.

[bobwhorn]

There have been some water flow issues but they always resulted in a high pressure shut down. From some data I have gathered, the 500 gph pump is marginal for two 16K units. I have some R410a coming so will give that a try. We were hoping to hold off on a bigger pump, too many other projects at the moment.
The lower step has a panel with the battery selector switch and the breakers for the bilge pumps built into it, so it doesn't look like it would be easily removed.
Bob

[ColRon]

bobwhorn, Bob, your top step is held in place by at least 4 screws. On mine, I can peel back the carpet to access the screws. Look closely at your top step, you may or may not have to remove the carpet to access the screws. Once you remove the screws the top step lifts off and will provide you with plenty of access to the unit. While you have it open check your AC filters too, it should be on the side of the unit facing the inside of the step where the inlet air vent is location.

[bobwhorn]

Thanks for the info. The carpet seems to be glued in place. I can access the filter through the air inlet vent, I'll look for screws again but they are probably under the carpet. But glad to know they are there, somewhere.
Bob

[ColRon]

If you carpet is glued down, the screws may go through the carpet, especially if this is the original carpet, so you will have to feel for them. Mine are also counter sunk, so the head of the screw sits below the surface of the step.

[bobwhorn]

Glad to know there is a way to replace the unit without cutting a hole in the bottom of the boat, The previous owners had the boat set up as an AirBnB, until the marina found out, anyway. The had all the upholster redone, inside and out and all new carpet. They were into appearance, maintenance not so much, so I'm pretty sure the carpet on the stairs is glued down.

What size AC units do you have on your boat and what size sea water pump? Our two 16K units are a bit too much for the 500 GPH pump. The unit in the cabin is new so it may have been replaced with a bigger unit.

[ColRon]

Glad to know there is a way to replace the unit without cutting a hole in the bottom of the boat, The previous owners had the boat set up as an AirBnB, until the marina found out, anyway. The had all the upholster redone, inside and out and all new carpet. They were into appearance, maintenance not so much, so I'm pretty sure the carpet on the stairs is glued down.

What size AC units do you have on your boat and what size sea water pump? Our two 16K units are a bit too much for the 500 GPH pump. The unit in the cabin is new so it may have been replaced with a bigger unit.

Bob, I also have two units. The one in the salon is a 16k unit, while the one in the state room is a 12K unit. I just replaced the one in the state room 2 years ago after the one original to the boat gave up the ghost. The Salon unit was replaced by the previous owner. I know the unit in the state room was original as I have the dealerships delivery checklist when the boat was first sold and the serial numbers on the check list and the unit matched. 30 plus years were on that old Marine Air unit, but when i brought the boat, I knew it was a question of when and not if.

As far as the size of the water pump, I'm not sure on its size. It is located in the bilge in front of the steps, but I've never checked to see what size it is. Next time i am at the boat i will check and see if I can determine its size.

[km1125]

The pump volume will also depend on the water temp. That 500GPH might work just fine with two 16kBTU units in some of the northern areas of the country, or on the west coast, but not in the southeast or Gulf coast.

If it was flowing a full 500 GPH (which they never due because of restrictions), then it's about 4,000 BTU for every degree F in temp that the water goes up flowing through the system. So to get 32,0000 BTU (two 16k units), you'd need a **minimum** of 8 degrees temperature rise. In reality, you might have half the 500GPH, so that would need a 16 degree rise. TEN is typically what's expected as a max. When you're starting in water 10F cooler, it's easy to get 10F rise. In water 10F hotter, it's much harder.