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Old 29-07-2012, 23:32   #1
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My Refrigerator is Tripping its Breaker

Hi all,
A month ago I went to my boat and the refrigerator had stopped working. It turns out it had tripped the breaker (10 amp). When I reset the breaker the compressor makes a humming sound for about 4 seconds and trips the breaker again. If I immediately reset it the breaker trips even faster. It's a custom 110v system that the last owner had installed by a company that is now out of business. It's air cooled, uses R-12, and has an older Tecumseh hermetically sealed compressor (by the nomenclature on the compressor I believe it was made in 1985). After some troubleshooting I excluded the breaker (replaced it), and the wiring to the unit (if I disconnect the compressor the fan, which is connected at the wiring box on the compressor unit itself, runs without tripping the breaker). I checked the starting capacitor and the relay with an ohm meter and both appear to be working properly. From there I pulled the relay off the compressor and checked the compressor coils via the terminals, these read within ~.5 ohms of each other (I believe this is within specs). At this point I think there is a mechanical problem with the compressor (it was made 27 years ago) and that it probably needs to be replaced.
Questions (my knowledge on refrigeration systems is limited but growing):
Does the pressure on the high and low pressure sides of the system even out when the compressor shuts off? If not, could the pressure on the high pressure side of the system have somehow become too high for the compressor?
Can anyone think of anything else I should be checking?
If the compressor needs to be replaced how involved would it be to replace it with a DC motor (I believe this would be more efficient than going through the inverter)? The compressor has a 'low' evaporation temperature rated at -10 deg. F, a 'high' starting torque, and a 1,500 BTU capacity (from the motor specs).
Many thanks for your input!
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Old 30-07-2012, 00:33   #2
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Re: My refrigerator is tripping its breaker

Are you sure that the starting capacitor is ok. That could cause the exact symptoms you are seeing.

Disconnect the capacitor and put your ohm meter (on low range) across its terminals. The resistance should first read low, but then rise as the capacitor charges from the voltage applied from the meter. Should level off at something greater than 10,000 ohms.

David
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Old 30-07-2012, 11:20   #3
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Re: My refrigerator is tripping its breaker

Thanks David. This is the test I did on the capacitor and it tested out well. I have heard that this test only tell us if the capacitor is not working but not that it is working properly. Perhaps changing out the capacitor would be a good next step. I would like to fix the system I have but only if it's an inexpensive fix. We're planning to go cruising on this boat and I want the refrigeration system to be more efficient. The usual dilemma, put more money into an old system or convert it to a newer more efficient system... thoughts?
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Old 30-07-2012, 15:36   #4
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Re: My refrigerator is tripping its breaker

Capacitors are cheap and although if it passes the simple ohm meter test it is probably ok. But it might be worth replacing just in case.

Let's hope Richard Kollman chimes in here. He is the pro on marine refrigeration systems (although yours doesn't seem to really be marine).

So here are some answers: Yes the high and low pressure equalize over time and unless the freon tubing somehow pinched shut while it was running, it should be the same as before the problem started.

It does appear that you have a mechanical problem with the Tecumseh compressor and any further effort (other than the cheap stuff you have done and maybe the capacitor) would be unwise. So I would replace the 110V system with a DC compressor system. The 110V compressors are usually significantly less efficient than a Danfoss DC compressor (which really runs at 300 or so volts AC internally).

One of the most efficient Danfoss based systems is the Frigoboat keel cooled system with the smart controller. The keel cooler uses sea water statically (it isn't pumped) which is colder and therefore more efficient than ambient air cooling. The smart controller adjusts the speed of the compressor to match the cooling load. I have a Frigoboat system on an 8 cu foot combined freezer and refrigerator space and it works very well.

But you may not have enough capacity for one of these. You say that your current system is 1,500 btu/hr. The Danfoss systems are less than half of that I believe. Go to the Frigoboat website and I think that they have some guidance on sizing. It all depends on the cu ft of freezer and refrigeration space plus the quality of the insulation that is installed.

David
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Old 30-07-2012, 16:05   #5
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Re: My refrigerator is tripping its breaker

Jonah, Go right to the compressor and first check and make sure it isn't bad. This is done with an ohm meter. On this youtube vid you want to do the "single phase" procedure. You will also want to check any terminal to a ground to check for a short. This will save you hours of trouble shooting and is what most techs do first.
http://youtu.be/6IiIIMcAVGE

System pressure will "equalize" on refrigeration units but it take a long time. suspect the freon charge last not first.

If you find the comp is bad it's more cost efficient to just replace the condensing unit or consider converting to 12volt system.

the Danfoss compressor is used by many makers of 12volt units. Norcold is an exception in that they use a "swing" compressor made by sawafuji and Norcold units are dual voltage 110 and 12 volt.
note also; the 12 volt units are much smaller capacity wise. you will need to determine the cubit ft size of your cold box.
Good luck!
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Old 04-08-2012, 21:54   #6
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Thank you all for the advice. I have checked the wiring on the compressor and it checks out, the ohm readings of the c-s plus the c-r added up to the s-r reading. That's what really points to a mechanical issue with the compressor. I'll find out how much a capacitor is and if it's cheap I might as well try it. If not, I think I'll begin to research the compressor/systems you all suggested.
Any further advice/opinions would still be very welcome.
Cheers!
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Old 04-08-2012, 23:19   #7
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Re: My refrigerator is tripping its breaker

If it comes to having to replace the compressor you will probably need to replace the whole system. Compressors need to operate into a specified restriction, either an expansion valve or a capillary of specified diameter and length. Your old system is unlikely to match. When the newer R-134a systems first came out there was much talk about the oil in the R-12 system being incompatible with the new refrigerant. About the only thing that might be worth saving is the evaporator, after a thorough flushing. So if the compressor is shot, start over.

I second the keel cooler recommendation - it is very efficient and quiet. The fancy controllers are nice but I think they are over-hyped - there is a wide variation in designs so look at the details.
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Old 10-08-2012, 10:32   #8
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Re: My refrigerator is tripping its breaker

Give compressor a tap with the mallet. It might be ceased. R12 is a pain. You are technically not even allowed to service the R12 unit yourself in the states.
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Old 10-08-2012, 10:49   #9
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Re: My refrigerator is tripping its breaker


Mallet, LOL good way to break the wire connections through the case... NOT recommended Try one of these Supco Solid State Relay & Hard Start Capacitor Pow-R-Pak SPP5 before you rip and replace. If it does have a run capacitor; They are usually shiny, round and or oval, battery like in looks with terminals on top. Some compressors have just a relay connected on the terminals under the cap where the wires go into the case.
good luck!
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Old 14-08-2012, 22:16   #10
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Re: My Refrigerator is Tripping its Breaker

Thank you again for all the input!
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Old 14-08-2012, 23:34   #11
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Re: My refrigerator is tripping its breaker

Quote:
Originally Posted by DeniseO30 View Post

Mallet, LOL good way to break the wire connections through the case... NOT recommended Try one of these Supco Solid State Relay & Hard Start Capacitor Pow-R-Pak SPP5 before you rip and replace. If it does have a run capacitor; They are usually shiny, round and or oval, battery like in looks with terminals on top. Some compressors have just a relay connected on the terminals under the cap where the wires go into the case.
good luck!
DeniseO30,
The compressor has a capacitor. I though it was a starting capacitor, not a running capacitor but perhaps they are the same thing... I'll do some reading. Will the Supco work with either?
Thanks again,
Jonah
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Old 15-08-2012, 12:25   #12
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Re: My Refrigerator is Tripping its Breaker

Quote:
The compressor has a capacitor. I though it was a starting capacitor, not a running capacitor but perhaps they are the same thing... I'll do some reading. Will the Supco work with either?
Start circuit is different from run circuit. Compressor may or may not have a start capacitor. Supco might help it start, considered a start capacitor, usually they call it a hard start kit.

There is a KLIXON PTC relay that can also go bad, When you try to start do you hear anything clicking?
It is possible the relay is bad and it is only trying to start on the run windings with the hum sound. Usually you should hear a rapid clicking noise. that relay is thermal and amp overload protection for the compressor.

More on that here
http://tech.akom.net/archives/31-Get...-the-part.html


If the compressor burned out inside then likely the system will need a complete flush out as it can make acids which when you put a new compressor in will corrode it.
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Old 15-08-2012, 13:19   #13
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Re: My Refrigerator is Tripping its Breaker

I'll give the hard start kit a try. But would this just be a temporary fix? It seems like if this works it means the starting capacitor is bad or the motor was mechanically stuck. Do the compressors get temporarly stuck sometimes?
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Old 15-08-2012, 13:26   #14
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Re: My Refrigerator is Tripping its Breaker

jonah-
"If the compressor needs to be replaced how involved would it be to replace it with a DC motor (I believe this would be more efficient than going through the inverter)?"
There are two different things hiding in there. The compressor, and a motor that turns it. All the electrical testing only tests the compressor motor--not the compressor itself. The compressor, or the motor, may have overheated or worn and seized up. That's why tapping it with a mallet is a valid test, to see if you can "unstuck" it without bashing its brains in.

The problem is that 27 years is more than the designed service lifetime, and you can't just bolt in new pieces and expect them to work. The compressor/motor assembly has to be sized for the volume, pressure, and type of gas in the system. And matched to the condensor and evaporator sizes. And unless those are made of the finest cupronickel and in amazing shape, after 27 years it is time for those to start having pinhole leaks and need replacement too. Or, if any moisture got into the system, that turns into acid and eats it out from the inside. R12 plus water becomes hydroflouric acid, one of the nastiest acids around. If there is a receiver/drier unit in the system, it is possible that after all these years it has clogged or broken down and caked up. That would also force the compressor to a stop.

The problem will be, no matter what you need to do, if the system is opened it needs to be vacuumed out with a "hard" vacuum before it can be refilled. And most shops just don't want to deal with R12 anymore. If you DIY on that, you're looking at breaking the laws (yawn) and trying to get real R12, not counterfeit or contaminated stuff sold on the gray market. So personally?

If I couldn't find an honest and reasonable local repair shop that didn't have a problem with R12? I'd say it is time to look at whole new systems. And that *may* actually be cheaper, too.
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Old 16-08-2012, 16:54   #15
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Re: My Refrigerator is Tripping its Breaker

Do not let comments about the 12 year old Clean Air Act intended to misdirect and confuse you stay on track with problem solutions. Excessive amperage during 110 volt compressor start up can be caused by a number of weak items Such as:
  • Thermo overload mounted under plastic cover outside compressor has burnt disc contacts. This is a $5 item and normally trips before circuit breaker. Bypass disc to test.
  • Starting amperage is most often slightly greater than twice running amperage, Example a Ĺ HP low pressure Tecumseh at 3400 Btu will have a starting load of 19 amps and running load of 8 amps.
  • Resistance in old boatís refrigerator wiring may also cause lower start voltage meaning higher amperage.
  • These 1500 Btu compressors normally always have a start relay and start capacitors so either one can cause compressorís armature not to rotate.
  • Because you are running compressor from 12volt to 110 volt inverter it may not be responding quick enough now in providing start up volts amps and cycles.
  • After every other possibility is ruled out mechanically locked rotor or shorted field coil would be indicated requiring compressor replacement.
  • Question, has anyone tampered with refrigerant in the past? Too much refrigerant will cause high amperage on start up especially in warm weather.

The first test I recommend is to connect refrigerator to a 115 to 125 volt shore power electrical grid.

Many marinas in remote areas have low voltage shore power problems and adding the
Kick Start piggy back large capacity suggested by Denise many times solves compressor electrical start up problems. Costs around $18

There are Quick replacement pre-wired Relay/Overload Combination for these compressors. Service techs normally carry a three way in their tool box.
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