AC trips breaker

[Erica C]

Our AC began tripping the breakers 2years ago, only when temps reach above 90-95.  Was told to clean coils, have done twice since that time.  No trouble last summer in Minnesota.  In April this year when we tried it the first time for the summer it turned on (had set to medium cool setting, as I usually do), but did not run right-sounded like a low hum, no cold air.  Fan settings and high AC worked.  Next day it worked fine.  Ran fine until very high temps of past 2-3 weeks (we’re in Louisiana this summer), now trips breaker in afternoon when temps are hottest.  Cooling the converter with a fan allows us to continue running it, altho not sure that’s the best plan…. When on, it blows very cold air.  We’ve been told different things by different repair people-it’s the freon, it’s the breaker; my husband thinks maybe the converter fan is bad, but only the AC causes it to trip.  

[Kirk W]

I suspect that you have an electrical panel that contains the converter, the 12V fuses and the 120V circuit breakers. A circuit breaker detects over current by use of a small heating element and when the maximum amount of current passes through it, that causes the breaker to open. When working properly they will trip instantly if the current is extremely high, after a minute or two at about the limit and after a longer period when close to the rated limit. For that reason, when the circuit breakers do not get the proper ventilation the ambient heat that builds up will effectively lower the trip setting of the circuit breaker. That is actually fairly common on some brands of panel. I have seen that problem with WAFCO combination panels many times. They use a standard household circuit breakers that were designed to be used in a typical home distribution panel with more air volume inside and ample room but install time into a compact box with several heat producing devices like the converter and many do not even provide a ventilation fan. Providing extra ventilation is the quick & easy answer and it is exactly what I did with my WAFCO until I had the time to replace it with one from Progressive Dynamics. The problem has not occurred since and I have used it for extended periods in hot weather for several years since the change with no need for the extra ventilation. You should also be aware that after a circuit breaker has tripped several times it will typically begin to trip at a lower and lower current flow so you might need to replace the circuit breaker when convenient. 

[lenp]

Concur with what Kirk said but another possibility is low voltage on the parks electrical system during the hottest part of the day when everyone is trying to cool down.  Low voltage equals higher current draw which could be contributing to your problem.  Suggest you monitor the line voltage at the park pedestal.

Lenp

[Case20hp]

One more thing to check is the electrical connections. I had a loose connection in my transfer switch for the generator on the shore power side and it would loose voltage when the AC was running. It burnt out an AC unit before we found the real issue. Eventually the transfer switch failed and that’s when we found the real issue with the AC. We added voltage and amperage monitoring to our 120 volt system so we can make sure we are getting good power. If we see lower voltage we start looking for the cause. Is it poor power at the campground or is there a bad connection. 

[Wrknrvr]

     Along with what has already been discussed.

   First thing I would test is the 12vdc batteries.       The reason I am saying this is that you say putting a fan on the converter will keep it operating. Check 12vdc batteries also with a meter. Do they feel warm to the touch. Are they full of water.

 

   So let’s say the 12vdc power drops low. To the point that the 12vdc power gets low enough to shut off the relay on the compressor.    But then it recovers quickly and turns the compressor back on. At that time it would trying to start on high pressure in the system. Normally you want a compressor to sit fore a few minutes. Before coming back on.

   So that would cause high enough amps to trip the breaker.    Also the incoming Ac power needs to be tested to make sure it is in the working range for your system. I think that would be 108 to say 125 vac.

 

   Another thought would be if other people are running ACs at the same time on the same power supply.

  Are you on 30 or 50 amp shore power.

 

  Just thinking,    Vern

[Wrknrvr]

   Are the filters clean

[oldjohnt]

Hi Erica, good questions, there may be multiple issues here so FWIW here are my thoughts:

1) The breaker tripping when it's hot and the AC is working hardest is likely (unless breaker is faulty which can happen with age and excess trips, try a new one) due to its THERMAL portion/function of a Thermal Magnetic breaker. That can happen even if the current is somewhat less than its 20 amp rating if it flows long enough and with the compressor running 100% at high temps such is possible even if all else is okay.

2) Your statement running a fan on the "CONVERTER" allows it to keep running raises some questions and flags. a) If you were operating off battery power (IE NOT shore power) via an INVERTER with a separate CONVERTER charging the batteries, the CONVERTER would be working extra hard which an external fan could help, HOWEVER b) If plugged to shore power and the utility (NOT Battery) is powering the AC yet cooling the Converter still helps, that sounds like the batteries may be low so the Converter is drawing max shore power supplied amps possibly dropping the voltage causing the AC to draw enough current to trip the breaker.     

SOLUTIONS TO THAT:

 When plugged to shore power try turning the CONVERTER OFF  and see if the AC continues to run?????? If so that tells me the house batteries may be low,,,,,, causing the Converter to run at max,,,,,,, stealing part of the available current,,,,,,,, causing a voltage drop,,,,,,,, causing the AC to draw excess current,,,,,,,,,,,,causing the breaker to trip  IE you may NOT be able to run Converter and AC at same time IFFFFFFFFFFF batteries are low or bad, ARE THEY ???? 

 Test the house batteries, if they are low or weak that causes the Converter to work hard so it draws max current leaving less power for the AC 

 My best guess is you are NOT powering the AC via battery and Inverter but shore power, so cooling the converter allowing it to work points to a battery problem !!!!!!!!!!!!!! or even a bad converter or any of its wiring connections

OTHER POSSIBLE PROBLEMS CAUSING BREAKER TO TRIP

1) Low AC voltage at the pedestal.  If voltage to the RV when under heavy load gets down much below 110 that causes the AC to draw more current LOW VOLTAGE MAY WELL BE THE PROBLEM check voltage when AC is running I SUSPECT IT MAY BE LOW

2) As mentioned above, low or weak batteries can cause the Converter to draw excess current HAVE THE BATTERIES TESTED INCLUDING A LOAD TEST and insure the water is above all the plates..

3) Loose/burned/resistive connections in the cords or plugs or receptacles or parks pedestal can cause a voltage drop under load THERE MAY BE A BAD LOOSE WORN RESISTIVE CONNECTION  NO TELLING WHERE dropping voltage.  

4) The AC unit itself, be it the compressor or CAPACITORS or low refrigerant  can cause the problem even if all else above is fine, but thats NOT my area of expertise, more for a HVAC expert, see what they have to say. The FIRST suspect would be the capacitors but I cant test that for you, need an HVAC technician.

SUMMARY OF SUSPECTS:

LOW VOLTAGE,,,,,,,Batteries,,,,,,,,,Converter,,,,,,,,,,Connections,,,,,,,,,,AC capacitors or compressor,,,,,,,,,,Faulty Circuit breaker,,,,,,,,,,,Short Cycling of the AC compressor (for whatever control circuitry issues) can cause excess current draw and trip out the Thermal or even Magnetic portion of the circuit breaker,,,,,,,,,Filters and cleaning issues as covered above........... 

Nuff said for now, best I have to offer, ask an HVAC Technician their thoughts??

PS While a Soft Start unit helps with high initial starting current surges, tripping when running is not something they help.

John T   BSEE,JD Too longggggggggg retired n rusty Electrical Engineeer so NO warranty and NOT any HVAC expert.

 

[Erica C]

The filters are cleaned regularly.

I appreciate all the tips, we now have several ideas of things to investigate.  The converter is right next to the water heater tank, which I end up turning on at the hottest part of the day so my husband can have a shower after work, that probably doesn’t help.

[Kirk W]

Do you use the water heater on propane or 120V? If you are using 120V the first thing to do is to change that to propane. If you have an infrared thermometer, measure the temperature of the assembly around the circuit breakers when early and again when it gets how and the a/c is running. I also agree with others that you should check to see what the voltage you have is both when the a/c is not running and again when it gets hot and the a/c is running as John makes a good point about the current draw increasing when voltage to the a/c falls. It is especially concerning if that voltage supplied drops lower than 108V. 

The converter could play a part, particularly if it has no cooling fan or if that fan isn't operating as it should. Since you are connected to shore power 24/7, the batteries should be maintained all of the time so a major recharging should not happen, unless the batteries are failing or weak. It seems that I am the only one who has dealt with the lack of ventilation to the circuit breakers but it can be a problem in some RVs due to a combination of the distribution panel design and the place that it is located. In a friend's 1996 Bounder we resolved that same problem by installing a small ventilation opening with a grill, thus increasing the passage of air naturally. In another we installed small muffin fan to a converter that didn't have one. All that one needs do is to look at the space allowed in any 120V code compliant distribution box to see that the combination panels used in many RVs do not allow the same space.

[oldjohnt]

6 hours ago, Erica C said:

The converter is right next to the water heater tank, which I end up turning on at the hottest part of the day so my husband can have a shower after work, that probably doesn’t help.

Being located next to the water heater can contribute to raising the ambient temperature in the immediate area, but many have adequate foam insulation so I don't see it as all that significant, but I just can't say from here. I agree with Kirk in that of you switch over to propane THAT WILL REDUCE CURRENT DRAW AND LESSEN VOLTAGE DROP PERHAPS ALLOWING THE AC TO FUNCTION WITHOUT TRIPPING THE BREAKER ???? Maybe running BOTH the AC and an elec water heater at the same time IS THE PROBLEM (Great suggestion Kirk !!!!!!!!!!!!!!!!!!!) but if there's adequate voltage to the RV while under load ?? you should still be able to run an AC plus an elec water heater at the same time no problem 

 If the above isn't the problem ??? and ifffffffffff EITHER cooling the Converter OR switching it off allows the AC to run and not trip the breaker, Im back to LOW VOLTAGE as a possible cause, be it at the Pedestal or voltage drops at other locations.

 Try turning off Converter and as Kirk suggested try running water heater on LP gas when AC is running and see what happens ??? take two aspirins and call me at the office. Regardless EITHER still contributes to LOW VOLTAGE (makes AC draw more current) as a possible cause ...Maybe even try a new circuit breaker, they can go bad and begin to nuisance trip !!!   

 Having fun yet ???

 John T   

Edited June 28, 2022 by oldjohnt

[D&J]

I did this for a living and nobody has come up with the first thing that should be checked and that's that amp draw with a amp probe. Without doing that it's just guessing. If the 12 volt is dropping off and the circuit is opening up and then restarting to soon the over current relay mounted on top of the compressor will cycle before the breaker tripping.

The amp draw had to be checked at the breaker panel and the connections at the same time, not just the breaker connection but the neutral also. Then checked at the unit and last at the compressors C terminal (common). The compressor amp draw will be less fan amperage. 

From experience 95% of the time with problem is at the breaker, it may be a bad connection or a weak breaker. You should also remove the breaker and check the connection where it clips on to the buss bar. Breakers by design will trip if they are run at 80% of rated trip amperage for long periods from heat and after they have tripped a few times that way they become weak and need to be replaced.

It could also be a weak run cap causing the compressor to draw high amps under the strain of full load on hot days.

Denny

[TXiceman]

Two of the things I tell new RVers to get and learn how to use are a volt-Ohm meter and a simple clamp-on amp meter.  With these two instruments, you can quickly solve a lot of problems or at least provide some meaningful information to people that are trying to diagnose your problem.

You do not need to spend lots of money on these two items.  You can get two separate instruments or just one combination unit as below.

Meter

Ken