What would cause an AC unit to drag the generator down?

[C lectric]

A clamp meter is a Clamp on Ammeter. It has a pair of jaws that can be opened and then closed over the wire you want to measure the current in.
You install it over one wire only. THere are some special circumstances but ignore those for now. Install over the BLACK of 120vac. It reads the current running through only that wire.

Get a unit that is rated True RMS. It makes a difference when reading some circuits. May not be needed here but it is often worthwhile so do it once.

Also in the same meter get one that reads DC current as once you get even a bit used to it you will find many other uses for checking currents not only in AC but in DC.
I would suggest as a good general purpose meter you want about a 0 - 200A or a 0 - 400A range.
Most of the AMP CLAMP meters will also have basic ohms, volts, maybe frequency functions. A decent unit will likely be in the range of $100-150.

There are many others that are more specialized and more money but for most purposes not needed.

I think once you have one you will realize its utility and advantages over any dash meters or only a DMM. Especially if you intend to do any troubleshooting of AC and/or DC circuits.

 

[Steve91T]

Hey everyone. We finally got home yesterday. Had an awesome trip. We did nothing but go to the pool, go out to eat, go to the beach, go out to eat and repeat. Amazing how nice it was to sit down and have someone bring us food and beer. We have definitely missed going out to eat.

Anyway, I never had a chance to trouble shoot the aft ac. This trip was about relaxing and enjoying ourselves. The other problem was that the ac compressor is under our 2 year old’s bed. So working on the ac after kids went to bed was impossible.

But, I spoke with a company who was recommended for bottom cleaning. Very nice guy. They basically have specialists for everything boat related, including an ac technician who has 30 years of experience. We agreed on a price to troubleshoot my ac and also take a look at my other two to make sure they are up to speed. I think it’ll be worth while to have a professional help me with this one.

The aft ac and central ac run off the same water pump. I have two different water discharges for this pump. One has always been strong flow. The other has always been week. I believe that whoever plumbed these systems has done something wrong and isn’t allowing proper water flow to the ac. Maybe it caused that ac to slowly burn up. Anxious to see what he finds. I’ll be down there while he is so we can crawl around together.

Anyway I’ll keep you guys posted. Thanks for all the help!

 

[GBPunky]

Steve, Is your vessel on the Lake or coast?

 

[Steve91T]

Steve, Is your vessel on the Lake or coast?

Coast

 

[GBPunky]

Where and who are you using if you don't mind me asking?

 

[Steve91T]

Where and who are you using if you don't mind me asking?

Saint simons island. A to Zincs. You familiar?

 

[GBPunky]

Saint simons island. A to Zincs. You familiar?

Gotcha, I am not. I would also recommend testing the capacitor before spending a dime.

 

[Boat]

Call your guy and ask him to bring capacitors with him.


Sounds like a thorough check-up is worthwhile, learning experience.


Buy the meter too. Ask the guy to show you a trick or two with it.

 

[MOJO]

Definitely check the capacitor first, but odds are you've got a failing compressor. Will cost you about 1/2 boat unit, maybe more to replace the compressor and that's assuming there's decent access for a technician. You can sometimes save $$$ by removing the unit yourself and sending it to the manufacturer or taking it to a shop and then reinstalling when it comes back. The debate you'll have is whether it's worth throwing dollars at an old unit or to replace the entire thing with new.

 

[rolomart3]

Partially obstructed airflow overloads AC conpressor

This comment applies upon interpreting your statement that "a short while after" means that the compressor successfully started with the generator": Make sure that enough air flows through the evaporator element, the component of the AC that cools the air.
If insufficient air flows through the evaporator, the refrigerant may cool all the way up to the compressor, which is a gas not a liquid pump.
Do you know what happens when a liquid is attempted to be pumped with a gas pump? The rotor locks.
In your case, it may be that the compressor does not cool enough fot the refrigerant to completely freeze at the evaporator. But it may form a mist with enough droplets to force the compressor into a serious overload.

Also, check the generator's fuel filter. If it is partially clogged, generators are notorious for shuting down due to fuel starvation while facing a temporary or sustained overload. Shutting down due to a dirty fuel filter should also occur when running more than on AC at the same time.

 

[kev_rm]

+1 on bad cap

Can your meter test capacitance, or microfarads? A crappy capacitor can cause all sorts of grief with a refrigeration machine. A good meter has that setting and a capacitor can be tested for zero bucks. If it is not in spec you are looking at ten or twenty bucks.

 

[BlindHog]

Have you checked your water strainer? I’ve had this problem from a clogged strainer or raw water lines that had crud in them.

 

[Barking Sands]

Test the caps..both start and run if it has both. Most modern multimeters can test those. Or just replace with exact specs since they are cheap enough. You can also test the compressor resistance. At the compressor. There is plenty of videos on how to do these things. Don't discount the run cap. Especially since your runs initially and then goes haywire after a short period. Hopefully you have access to these places. And if it's not something easy...I just replaced my 16k btu unit with a Marinair unit for $1700. It was easy to install and works great. I had a bad compressor. It made no sense the replace a compressor on a 20 year old unit for half the price of a new one.

 

[GBPunky]

This comment applies upon interpreting your statement that "a short while after" means that the compressor successfully started with the generator": Make sure that enough air flows through the evaporator element, the component of the AC that cools the air.
If insufficient air flows through the evaporator, the refrigerant may cool all the way up to the compressor, which is a gas not a liquid pump.
Do you know what happens when a liquid is attempted to be pumped with a gas pump? The rotor locks.

'm embarrassed to say I just had a tech inspect an A/C that was tripping only to find I had blocked off the return with a folded table!Thank goodness he was honest! Always start with the basics.

 

[Comodave]

'm embarrassed to say I just had a tech inspect an A/C that was tripping only to find I had blocked off the return with a folded table!Thank goodness he was honest! Always start with the basics.

It’s always the simple stuff that gets overlooked. Well at least you got it fixed.

 

[Alaskan Sea-Duction]

Thanks for the update.

 

[ORIF]

I may be missed other symptoms in the above thread but you mentioned low water flow from one of the ac units and that the offending unit got hot.

I just had an issue where one of my air conditioning unit compressors would turn on fine then trip the breaker a few minutes later.
Also seemed pretty hot as you noted.

When initially turned on, the amps slowly increased until it tripped the breaker.

My problem was low flow through the raw water cooling system.
It was resolved after running barnacle buster through the raw water loop for that AC.

I left the strainer and the pump out of this acid cleaning loop. Some say it's ok to run Barnacle Buster through the pump and some not. The pump seemed to be working fine so I used a separate spare bilge pump that I use when flushing the engines.

Worked so well on unit #1 I decided to clean the the raw water loops of the other 2 units. After doing the second, this previously functioning unit started kicking off. That's when I learned an air pocket can cause similar symptoms and I needed to bleed it out which got that one back on line.

Now ac unit #2 ran great but seemed to be having low raw water flow while the other had good output flow.

So I went back the the common part of the raw water loop previously omitted - the strainer and thruhull. Probably should have started there but the other steps still needed doing.

Took the strainer apart and cleaned it. When I opened the thruhull after cleaning the strainer the flow I had would not have sunk the boat any time soon. Hooked a dock hose up to the hose coming from the thru hull using a hose barb with a screw-in hose fitting on the other side, opened the thruhull and turned on the hose. I could feel initial resistance then high flow through the dock hose as it blew out whatever was causing the obstruction.

Both AC units now running great. Getting to the 3rd unit is going to be more difficult.

Figured most of this out by reading threads on this site.

Sounds like you also need an emergency wine stash on your boat.

 

[Steve91T]

Process is being made! So yesterday we had a diver clear the intakes and a super nice ac guy (who’s been doing marine AC work longer than I’ve been alive).

AC guy found that nothing is wrong with my compressor! Only problem was that it didn’t have enough water flow. The water lines were spliced together garden house and they were failing. His 1 1/2 hour on the boat was absolutely worth it. I learned a lot. Great guy! He could have made some crap up about needing a new ad unit but instead he told me that I just need to run new hose. So nice to find honest people.

Anyway, my dad is down here helping me work on the boat. We grabbed new water line and fittings. We taped the new hose to the old hose and I was going to just pull it through (has to go from the mid cabin to the engine room). Problem was the hose wouldn’t budge. We found bags of sand next to the ac unit sitting on top of the water lines to and from the ac unit! Can’t believe someone did that.

Ran the new hose and man she started flowing like crazy! But the pump keeps losing the prime. It’s been doing that lately. So we found the filter housing to be sucking air and leaking. It feels like there’s a crack near the bottom and water was spraying out. Looks like it’s had a slow leak for a while.

So guess I’ll replace that. Hope west marine has one in stock.

Anyway, like I said, process is being made!

 

[BlindHog]

Glad you got it figured out. I hope you gave the ac guy a big cash tip! Always keep them in your good graces. I’ve seen more issues from raw water problems then anything else and running acid through them is a must once or twice a year in warm saltwater areas to keep the flow up.