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Old 08-28-2016, 11:37 AM   #1
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Air conditioning repair

We discovered last week, by finding our Coon Hound with a wet ear, that the salon air conditioner's condensate pan was overflowing. Turns out that the drain hose went 'up' before it went 'down'. Apparently, running the AC for several days in humid heat was enough to fill the pan but not by running it for shorter periods.

So, I bailed out the under-settee spaces and re-routed the drain hose so that gravity would have effect. I so doing, I either slopped water on the wiring's split-type corrugated tubing, or the wiring had been laying in water for long enough. The AC began 'spatting' and the motors began hesitating. Shut it down, moved the wiring bundles out of the remaining water and went home, thinking that a week would be enough to dry things out.

Went down this weekend and...not. Spent several hours on my knees in 90 deg humidity, un-cabling the wiring, re-routing it, and trying to find where it was shorting. Unsuccessful for a number of hours; each time I did something I'd try the system, spatting would continue. Finally, I opened up the control box which would sound and smell like a spark with the spats. No water showed anywhere. However opening the box gave me the ability to unplug a cable and re-rout it neatly and definitively out of the condensate. All became well. And stayed well after I reassembled and re-cabled everything.

We were out on a mooring, running the genset. Each time any of the three compressors started, the genset revs would hesitate a moment. I have almost learned to ignore it. Should I?
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Old 08-28-2016, 12:00 PM   #2
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Not necessarily.

Do you A/C units have soft starts?
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Old 08-28-2016, 12:49 PM   #3
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If you have three A/C compressors you must have a pretty big generator. What size? And can you measure the amps that your boat draws when all is running? Those answers will tell whether you have a potential problem. If you do, adding soft start kits to the three A/C systems will probably solve it.


Supco makes an inexpensive soft start kit. Dometic makes a much more expensive, but better one.


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Old 08-28-2016, 01:50 PM   #4
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David, two AC compressors and one refrigerator compressor. 9kw Northern Lights. I do not have an ammeter for the electrical system as a whole, nor an electron counter. We do seem to run through a battery charge pretty quickly while running the NorCold on 12v.

Capt.Bill11, no I certainly do not have soft starts. Sounds like a good 'add'.

Actually, I Googled, they're called 'hard start kits'. Our unit is labeled SeaMach, apparently sold in various guises.
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Old 08-28-2016, 02:08 PM   #5
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Most ac systems require loop in them to prevent backflow from the condensate pan below the coils.If it is not in there,then the water winds up not draining because of the pull of the fan,and that will definitely cause the water to surge back and forth.
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Old 08-28-2016, 02:17 PM   #6
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tinped, my salon AC drain hose exits the side of the pan, leads sideways about 10" and drops through the deck, drains into the bilge. I presume the forepeak AC does the same. I've got some 3/4" PVC piping wandering around the ER which I had thought was for condensate, but must be for raw water supply to the condenser coils.
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Old 08-28-2016, 02:20 PM   #7
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OK, two A/C units, probably 16,000 btu each. They will pull about 15 amps each and the fridge will be irrelevant. So with nothing else running like a microwave, hair dryer, water heater, etc. you are pulling 30 amps or 3,600 watts, which is low for a 9 kw Northern Lights. And the starting current shouldn't phase it.


Connect a voltmeter to the terminals on the A/C and measure the voltage there and at the generator output. You may have a bad connection and that will show up as a voltage drop. I would worry about anything more than a 5 volt drop. Also check the voltage when the A/C compressor kicks in. It might drop 10 V at the A/C terminals and move a few volts at the genset output when the compressor kicks in. Any more and you probably have a bad connection somewhere.


Your 9kw NL generator should be able to start both A/Cs with no problem and no soft start kit.


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Old 08-28-2016, 02:35 PM   #8
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Thanks, djmarchand, I would have been running the HWH, and I do hear the genset change pitch when I switch it on. Of course, after initial starts, the loads for the HWH and the ACs come on at intervals that I do not determine. The genset starts the compressors but 'lets me know' when the load comes on. I should say that the loads don't really change the pitch since whatever controls the fuel supply to the gen's engine keeps the RPM the same whatever the load, but I do hear the difference.
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Old 08-29-2016, 06:14 AM   #9
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the genset revs would hesitate a moment. I have almost learned to ignore it. Should I?

IF the noisemaker takes the load , no problem.

An air cond motor will frequently require 3X the operating amps for a split second on starting

Called LRC. Locked Rotor Current

It will require even more juice if the unit has just shut down and the compressor has to start against high head pressure.

The RV folks with modest sized power hoses and smaller noisemakers are used to this and will install a device that keeps an air cond from restarting with out a 2 or 3 min delay.Some AC have it factory built in.

For really small power they use a device that will only allow one unit to operate at a time.

You can also install a priority relay to do automatic load shedding ( $60.or so)

The fridge , freezer or HW heater will be shut off when an air cond starts.
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