A/C Breaker Tripping

anaviator · 09-14-2020, 07:23 AM

Over the past couple of trips, our front roof air has started to trip its breaker periodically. The breaker resets ok and the unit starts back up with no problem. This past weekend, the rear / bedroom air conditioner did the same thing (although it has only done it once).

I thought maybe there was something wrong with the front a/c unit but now that the rear air has done it as well, I'm wondering if something else is going on. Has anyone else run into this?

I have an appointment at our local dealer next month and will have them take a look but I thought I'd check and see if anyone on the form had run into this. The chances of two a/c units failing on a 7-month old unit seem pretty slim.

**Bama Rambler** · 09-14-2020, 08:28 AM

Does your EMS show low voltage when it trips?
What does the EMS show for the voltage?

Since both of them have done it randomly, I'd suspect low voltage when the compressor is kicking back on.

anaviator · 09-14-2020, 08:36 AM

I have an external / portable EMS and it has not shown any errors. This is also happened at several different campgrounds (and with the 50-amp hookup we have at home) so I don't think the problem is related to a shore power issue. It is interesting, though, that with the front AC breaker tripped, the Precision Plex "Line" page on the power menu will show one leg pulling amps with zero volts and the status page shows the "unplug immediately" warning message. As soon as I reset the breaker, everything returns to normal.

So far, only the front and rear A/C units have done it. They're the ones that get the most use, though - the front is always warm due to the poorly insulated cab and windshield, and the bedroom gets a workout at night because we like it fairly cool when we sleep.

clr · 09-14-2020, 08:58 AM

I would look at my plugs on both ends of my power cable. They can get dirty with use over time. This can cause a poor or loose connection that will cause a higher than normal voltage drop. Where you have a voltage drop it will cause heat, and can lead to the melting of the plug. Take an emery cloth or similar and clean the contacts and make sure all the connections are tight. For your safety please insure that all power is off while you are doing this.
If this was me I would also pull the fuse box out of the wall and make sure all connections for the AC power are tight. I may even pull the connector for the AC on the side of the unit and make sure that all connections are tight.

anaviator · 09-14-2020, 09:09 AM

Thanks, Chuck - I'll check all of the connections. I did notice that the breaker is a little warm when I've reset it.

**Bama Rambler** · 09-14-2020, 09:25 AM

Quote:

Originally Posted by anaviator

I have an external / portable EMS and it has not shown any errors. This is also happened at several different campgrounds (and with the 50-amp hookup we have at home) so I don't think the problem is related to a shore power issue. It is interesting, though, that with the front AC breaker tripped, the Precision Plex "Line" page on the power menu will show one leg pulling amps with zero volts and the status page shows the "unplug immediately" warning message. As soon as I reset the breaker, everything returns to normal.

So far, only the front and rear A/C units have done it. They're the ones that get the most use, though - the front is always warm due to the poorly insulated cab and windshield, and the bedroom gets a workout at night because we like it fairly cool when we sleep.

The part I highlighted sounds like the Plex voltage sensor is on the front A/C branch circuit, but the current transformer is on the incoming power wire. While not ideal I don't know that, it's a problem.

I agree that you should check all the electrical connections tightness.

edgewant · 09-14-2020, 11:07 AM

Probably too coincidental but the breakers themselves could be weak.

anaviator · 09-14-2020, 12:04 PM

I checked the connections at the breaker box and they were tight - really tight. Just for fun, I swapped the breaker set for the front A/C / front floor heat and the mid A/C / fireplace. That should at least answer the breaker question if the problem follows the breaker or remains on the same circuit.

We're headed back out this upcoming weekend and will see how things shake out.

Maingler · 09-14-2020, 05:29 PM

Quote:

Originally Posted by Maingler

This might help in diagnosing your issue.Attachment 239139

Berkshire RV Power Presentation.pdf

anaviator · 09-14-2020, 07:17 PM

Thanks for that info! It's helpful to know which circuits are on each leg.

In this case, I have power to all components and on both legs at all times.

It is interesting, and rather strange looking at these diagrams, that my Plex panel shows zero volts on line 1 if the circuit breaker for the front AC breaker is open, zero volts on line 2 if the mid AC breaker is open, and "No Service" if both are open (but everything other than those two ACs still has power).

**Bama Rambler** · 09-15-2020, 12:14 PM

Quote:

Originally Posted by anaviator

It is interesting, and rather strange looking at these diagrams, that my Plex panel shows zero volts on line 1 if the circuit breaker for the front AC breaker is open, zero volts on line 2 if the mid AC breaker is open, and "No Service" if both are open (but everything other than those two ACs still has power).

The Plex has two voltage inputs and as long as they're on different phases it doesn't care where the power comes from. The installing tech just picked two breakers on different phases and they just happened to be the A/C breakers.

The current donuts should be on the incoming lines before any of the RV breakers, so that's why you can read amps with the A/C breakers off.

anaviator · 09-15-2020, 02:16 PM

Ahhh, gotcha. It didn't occur to me that the current and voltage monitors would be different. That makes perfect sense as those two breakers happen to be the first two downstream of the mains.

dave-g · 09-16-2020, 04:00 AM

Quote:

Originally Posted by Maingler

Attachment 239141

Nice drawing you did.

anaviator · 09-19-2020, 08:42 AM

A quick update - after swapping the front and mid air conditioner breakers, we're seeing the same problem at another completely different campground.

Again, no low voltage events recorded by my Progressive EMS so I don't think low voltage is causing the compressor to pull excessive current. As in past events, everything else works just fine - it's just the one breaker that trips. I should also note that the fan runs fine - the breaker won't trip if just the fan is on.

I'll add this issue to the list I have for my dealer appointment in a few weeks. Hopefully they can get it figured out.

red0801 · 09-21-2020, 01:08 PM

Quote:

Originally Posted by anaviator

A quick update - after swapping the front and mid air conditioner breakers, we're seeing the same problem at another completely different campground.

Again, no low voltage events recorded by my Progressive EMS

What type of Progressive EMS are you using?

anaviator · 09-21-2020, 01:14 PM

We have Progressive's EMS-PT50.

Nightshifter · 09-22-2020, 07:33 PM

If you have a clamp on type ammeter with a max amp setting put it around the conductor connected to that breaker. Then when the compressor kicks in you can see exactly what it was drawing causing it to trip. It’s more than likely a locked rotor condition in the compressor.

anaviator · 09-22-2020, 08:41 PM

Quote:

Originally Posted by Nightshifter

If you have a clamp on type ammeter with a max amp setting put it around the conductor connected to that breaker. Then when the compressor kicks in you can see exactly what it was drawing causing it to trip. It’s more than likely a locked rotor condition in the compressor.

I was able to watch the amp draw on the plex screen when the compressor started up a couple of times. Most of the time it only adds a couple of amps when it starts but I caught a jump to 41 amps on one cycle that is the likely culprit. It doesn't do it all the time, though, and it seems like it will trip after running for a while as well - not just on start up.

The coach is going to the dealer in a couple of weeks to get another issue taken care of (the icemaker / fridge water line sprung a leak while on a trip a couple of weeks ago) so they're going to look at it then.

It's always something...

formerFR · 09-23-2020, 09:56 AM

I would detach any shore power, then open your main panel and check the tightness of the black wire coming out of each a/c breaker - they may have worked lose, and when the wire heats up, it may then 'move' and arc and trip the breaker. This happens in a lot of RVs when you start using these high-draw amperage appliances, especially during the hot summer months when the ambient temperature is already up there anyway.

anaviator · 09-23-2020, 10:08 AM

Quote:

Originally Posted by formerFR

I would detach any shore power, then open your main panel and check the tightness of the black wire coming out of each a/c breaker - they may have worked lose, and when the wire heats up, it may then 'move' and arc and trip the breaker. This happens in a lot of RVs when you start using these high-draw amperage appliances, especially during the hot summer months when the ambient temperature is already up there anyway.

Thanks for the advice. I actually removed the breaker and swapped it with one of the other Air Cond breakers to rule out a problem with the breaker itself and then changed it back. The connections are good and tight.

I think there is an issue with the compressor on that specific Air Cond unit. We'll see what the shop finds when it goes in next month.

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