Air Conditioning Power Problem

[RyanB]

I had my original (I think) AC pump crap out on me, so I installed a new March pump unit over the weekend, which fixed the problem. When we got back to the dock later that day, all was working and we had the AC running for 3-4 hours. All of a sudden the entire system just stopped, like someone shut the breaker off.

I looked at the AC panel, the breaker was still on. I went to the 50amp breaker on the dock, that too was still on. So I went back to the panel, shut the breaker off, and noticed my Air Conditioning supply power light was just barely illuminated. You could only see a faint glow from the bulb, while the Ship Service light was perfectly bright (see pics below). When I would turn the breaker on, the light would go out completely. Turn the breaker off, and it would then again dimly glow.

Any ideas what could be going on? Everything I'm reading seems to point at reverse polarity, but how would that happen while the AC system is on and running perfectly fine? I'm leaning more towards insufficient power from the shore, but again, it would have had to drop during use and never came back.

I have one 50amp shore power pigtail plug that splits and feeds two 30amp lines to the boat.

Hoping someone else has dealt with this and its a rather easy answer and fix.



Breaker turned off, dim light



Breaker turned on, completely off

 

[Pascal]

Do you have fuses or breakers at the shore power inlets? What kind of boat? 2 30 amps cords isn’t much. One will just run two air cons.

 

[RyanB]

Do you have fuses or breakers at the shore power inlets? What kind of boat? 2 30 amps cords isn’t much. One will just run two air cons.

Its a '86 36 Sedan. It has 2 shore power inlets in the cockpit, one cord supplies the "ship service" the other supplies the Air Con. Both are 30amp, each inlet has (2) 30 amp fuses at the connections. I replaced the fuses, at the air con inlet, with new fuses I had on board but nothing changed.

Side note - How do you know if those fuses are blown? They looked fine and were on slightly warm.

 

[RyanB]

It should also be noted that the supply power gauge is bottomed out, showing no incoming power on the air con, but full power, 120v on the Ship Service.

 

[Captain Ralph]

If you do not have remote service power inlet breakers, Then I would suspect a fried 30A cable and/or inlet hardware.
Also Inspect the back side of the A/C 30A inlet.

 

[Pascal]

You should be able to test the fuses for continuity

Start at the pedestal and check for voltage at each connection. The 50 amp outlet will have two hots. Each should show 120v against the common neutral. After the splitter each 30 amp cord will have a single hot and a neutral. Each hot should also show about 120v. Keep going down the line till you loose voltage reading on that leg.

If not a cord or plug problem, check the fuse holder at the inlet. They re known to cause problems

 

[RyanB]

You should be able to test the fuses for continuity

Start at the pedestal and check for voltage at each connection. The 50 amp outlet will have two hots. Each should show 120v against the common neutral. After the splitter each 30 amp cord will have a single hot and a neutral. Each hot should also show about 120v. Keep going down the line till you loose voltage reading on that leg.

If not a cord or plug problem, check the fuse holder at the inlet. They re known to cause problems

Thanks, I'll start to check on this right away. The cords are about 3 months old, but could have fried.

 

[madhatter1]

Find a friend that has a meter and knows how to use it.

 

[SKYCHENEY]

Blown inlet fuse. If you don't know how to check them, put in a spare. If you don't have a spare, swap out with the one for other inlet.

 

[Captain Ralph]

Do all Hatts have this problematic fuse?
Is there not a lamp on the top-cap that lights when the fuse is blown?

My base of issue; Drawing many amps of power down this big heavy cable that you paid dearly for.
Then all that fat wire comes down to a lil problematic thin wire suspended in a lil glass tube.
Then back to big heave wire cables. And it works at all?
Well, That is the power / fuse thing. Somehow they can conduct lots of current. But they self destruct at the wrong time. Why not a breaker?

O K done with that.

We have witnessed so many 30Amp service connects fail on lots of different brands of boats. The first sign is the black wire nice and crispy behind the male service in receptacle.
The black Hubble insulators can take some heat but the Marinco melts. But that out of site black wire is still fried.

 

[rustybucket]

We blew a dock breaker this past weekend. Two phase breaker, only one side goes bad. It presents really weird issues and meter readings. Sounds like maybe something you should check.

Pretty easy to check with a multi meter if you have a basic understanding of AC power.

 

[Pascal]

Do all Hatts have this problematic fuse?
Is there not a lamp on the top-cap that lights when the fuse is blown?

My base of issue; Drawing many amps of power down this big heavy cable that you paid dearly for.
Then all that fat wire comes down to a lil problematic thin wire suspended in a lil glass tube.
Then back to big heave wire cables. And it works at all?
Well, That is the power / fuse thing. Somehow they can conduct lots of current. But they self destruct at the wrong time. Why not a breaker?

O K done with that.

We have witnessed so many 30Amp service connects fail on lots of different brands of boats. The first sign is the black wire nice and crispy behind the male service in receptacle.
The black Hubble insulators can take some heat but the Marinco melts. But that out of site black wire is still fried.

Many of them have those fuses that have caused plenty of problems and fires. It is so easy to replace them with a breaker installed in a standard shorepower cover.

 

[rustybucket]

Many of them have those fuses that have caused plenty of problems and fires. It is so easy to replace them with a breaker installed in a standard shorepower cover.

You have a recommended part to do the swap? We are still on fuses, but it's on my list.

 

[Pascal]

You have a recommended part to do the swap? We are still on fuses, but it's on my list.

Here an ELCI version with plastic cover. You can also find the non ELCI breakers in a chrome cover

https://www.greatlakesskipper.com/m...SLIHb91TuFz6st7lh0hadNz9MVu7Bb2xoChnoQAvD_BwE

 

[RyanB]

Blown inlet fuse. If you don't know how to check them, put in a spare. If you don't have a spare, swap out with the one for other inlet.

This is a stupid question, but I'm asking anyway (still learning). Are these fuses directional? I swapped with spare I had on the boat, but didn't have meter check, and no change. I have the below, with different top and bottom points. I'm assuming it isn't directional as its an inline, but wanted to double check.

 

[Modman]

Fuses are not directional. The one you show, however, is a "rejection" type fuse. If it is used with a "rejection" type fuse holder it will only fit into the holder in one direction.

 

[RyanB]

Blown inlet fuse. If you don't know how to check them, put in a spare. If you don't have a spare, swap out with the one for other inlet.

This was it. I had two blown fuses. One in the Air Con inlet and the other in the spare fuse box on the boat, that I was replacing the inlet fuses with. As luck would have it, I must have been replacing my blown inlet fuse with the blown spare.... starting fresh now with all new and new spares.

Another question though. This must have blown when I had both AC units running at the same time. I've ran the AC/Heat, in the salon, all day/night alone and no problems. But this past weekend I cranked the salon and state room AC unit on at once and it popped the fuse.

Is 30amps not sufficient to run both? I looked in manual but nothing states to only run one unit at a time.

 

[SeaEric]

The short answer is yes. 30 Amps is right at the edge with 2 AC units running. This is why I just did a complete re-do of my electrical and took both inlets up to 50 Amps. I can now run everything all at once. When these boats/wiring/connections/equipemt were all brand new - it worked. Add some age to all of it and not so much.

 

[Pascal]

Depends on what size the ACs are. 16k btu usually use about 13-15 amps each so with the pump you ll be close to 30amps. Also older units will use more power than newer

Also, avoid turning them on at the same time so both compressor don’t surge at the same time

 

[Captain Ralph]

It's close. A bad connection, low dock service, tired compressor, something else on that fuse drawing some extra amps (raw water pump, added charger, ??), bad compressor start cap.

Hard to do, you have to watch your amp meter and determine how much current you are (trying) to draw.

Wonder if you could run fine on your gen-set.

Just had an event a couple of nights ago on our boat. One of our A/C units displayed a L/AC error. Low electricity.
Not in a hurry, I just turned the display off (Passport I/O). I'll get to it later.....
That night, I noticed our lil get-set cycling a load about every 20 seconds, WTF.
Did not stop till I opened the breaker to that faulted A/C unit.
Yep, Bad cap.
When you turn the op panel off, one side of 230Vac (115Vac) is still hot to the equipment.
On a 30 amp / 115Vac shore power supply, this would of popped a fuse in a NY Second.

Why I mentioned this, After checking your shore service connections (Inside and outside), do not rule out things you don't usually think of. A boat is full of surprises.