Dometic ac unit replacement
- Thread starter Edw
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wahoo33417
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I have installed a new Mermaid Marine AC in my 2007 Sailfish that did not come with AC from the factory. That may or may not be as hard as replacing yours depending on where it is and if the connection points (hoses, clamps, filters, wires, etc) are still in fair shape.
So where is your AC unit located?
And are you sure the entire unit needs to be replaced? Not just the easier things like the thermostat or the main computer (if mounted separately)?
Rob
So where is your AC unit located?
And are you sure the entire unit needs to be replaced? Not just the easier things like the thermostat or the main computer (if mounted separately)?
Rob
Location is under the sink to the left of Refrigerator. I have to remove the old one. New unit $2k. Existing unit motor assembly
Rusted fan is froze just hums and blow the breaker. Very tight spot to work in.
Ed
Rusted fan is froze just hums and blow the breaker. Very tight spot to work in.
Ed
wahoo33417
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Ed: So how much do you like your refrigerator? 
.
You're not kidding about that being a tight spot.
Speaking from my 2007, the fridge comes out pretty easily. I recall there being trim pieces at the top and bottom to remove. After that, it's pulling the fridge by each side in turn, bit by bit, until you can reach back and disconnect the 12 volt plug in the back. (I replaced the fridge with a custom built cabinet.).
As for the AC, my thoughts, and I'm no mechanic, are to first remove and get out of the way the things you least want to damage. Obviously, if somethings present themselves as needing to go first, they go first.
For me, I would want to remove the clamp that holds the ducting in place and maybe tape the ducting well out of the way. That is the thing I least want to do again.
It would be best to have a schematic, or at least a picture of your unit to help you find the following three hoses.
1. A small (1/4"?) hose coming from the drip pan that the AC sits in. This hose likely runs to your shower sump or less likely just empties into your forward bilge.
2 & 3. Two (3/8"?) hoses coming off the coils of the AC. One will bring cooling water in from a water pump located near a through-hull. This could be in your rear bilge. The second hose discharges that same cooling water overboard through a fitting above the waterline near the cabin. I don't know which side on your year. If you can, label these hoses before you pull them off.
You probably want to look at all the hoses as best you can and consider replacing them if you see any bit of dryness or cracking that gives you pause. These hoses are pumping hundreds of gallons of water per minute beneath the waterline of your boat and out of sight.
At least from what little I know, most AC units have a separate control box, or ECU or 'brain'. You'll obviously need to unplug it from the AC, hopefully a simple harness. But, if you can, look over the ECU and make sure all the connections are good and not corroded.
If you can, follow the wiring from the ECU to the thermostat to make sure none of these thin wires have dried out and begun to shed their sheathing over the last 23 years.
My most embarrassing moment of late came when my AC wouldn't turn on no matter what I did. It took several minutes of real worry about our upcoming boat trip before I thought to put a new battery in the thermostat. After about 5 minutes of recycling in the ECU it came back on just fine.
Not suggesting that the battery is your issue at all, you know it isn't, but while you're in there, you may way want to take a look inside the thermostat and clean any contacts of corrosion. Or, if yours is like mine, a non-programmable thermostat can be had on Amazon for $28 that looks just like what came with my unit.
Oh, and see if you can find a lanky 12-year-old to do all this!
Good luck.
And I'm sure more knowledgeable people on this great forum will chime in with helpful information.
Rob
.You're not kidding about that being a tight spot.
Speaking from my 2007, the fridge comes out pretty easily. I recall there being trim pieces at the top and bottom to remove. After that, it's pulling the fridge by each side in turn, bit by bit, until you can reach back and disconnect the 12 volt plug in the back. (I replaced the fridge with a custom built cabinet.).
As for the AC, my thoughts, and I'm no mechanic, are to first remove and get out of the way the things you least want to damage. Obviously, if somethings present themselves as needing to go first, they go first.
For me, I would want to remove the clamp that holds the ducting in place and maybe tape the ducting well out of the way. That is the thing I least want to do again.
It would be best to have a schematic, or at least a picture of your unit to help you find the following three hoses.
1. A small (1/4"?) hose coming from the drip pan that the AC sits in. This hose likely runs to your shower sump or less likely just empties into your forward bilge.
2 & 3. Two (3/8"?) hoses coming off the coils of the AC. One will bring cooling water in from a water pump located near a through-hull. This could be in your rear bilge. The second hose discharges that same cooling water overboard through a fitting above the waterline near the cabin. I don't know which side on your year. If you can, label these hoses before you pull them off.
You probably want to look at all the hoses as best you can and consider replacing them if you see any bit of dryness or cracking that gives you pause. These hoses are pumping hundreds of gallons of water per minute beneath the waterline of your boat and out of sight.
At least from what little I know, most AC units have a separate control box, or ECU or 'brain'. You'll obviously need to unplug it from the AC, hopefully a simple harness. But, if you can, look over the ECU and make sure all the connections are good and not corroded.
If you can, follow the wiring from the ECU to the thermostat to make sure none of these thin wires have dried out and begun to shed their sheathing over the last 23 years.
My most embarrassing moment of late came when my AC wouldn't turn on no matter what I did. It took several minutes of real worry about our upcoming boat trip before I thought to put a new battery in the thermostat. After about 5 minutes of recycling in the ECU it came back on just fine.
Not suggesting that the battery is your issue at all, you know it isn't, but while you're in there, you may way want to take a look inside the thermostat and clean any contacts of corrosion. Or, if yours is like mine, a non-programmable thermostat can be had on Amazon for $28 that looks just like what came with my unit.
Oh, and see if you can find a lanky 12-year-old to do all this!
Good luck.
And I'm sure more knowledgeable people on this great forum will chime in with helpful information.
Rob
Yes have removed refrigerator that is the easy part. Will replace that too. Norcold NR 740 refrigerator. New AC unit from West Marine Domteic 6000 btu ECD R-410A. Is a direct replacement for old unit complete with new controls. All ductwork stays. Old unit is foamed in difficult working on it. Yep need that 12 yr old!!
wahoo33417
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Ed: Great that you found a direct replacement. But foamed in!? I'm not sure my body would be happy tackling that!
I got the old one out!! It was installed over a.25 inch rubber pad with plastic wrapped on bottom and pan sides I think to prevent sticking of the foam which I cut away with a fish fillet knife. Waiting on arrival of new one now
wahoo33417
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