AC Unit intermittent surge problem

[JohnD]

I'm doing a solar install and have found that my Victron Multiplus keeps surging and throwing errors intermittently. I've tracked it down to the AC breaker. With the AC breaker off (its 30 degrees, so it shouldn't be running anyway), the problem disappears. So, I'm wondering if anybody has experienced something like this. Why would an AC unit have a power spike intermittently when its 30 degrees outside and presumably off? I have recently installed an easy start, but hadn't experienced any issues prior to the solar/battery install.

[Jkwilson]

Any association with the furnace cycling? Heat strip in the AC?

[JohnD]

The furnace was not on when I was troubleshooting the problem, so I would say no. I'm not familiar with a heat strip in the AC. Can you please clarify?

[Jkwilson]

The furnace was not on when I was troubleshooting the problem, so I would say no. I'm not familiar with a heat strip in the AC. Can you please clarify?

Some air conditioners have an option for an electrical heat strip to allow the unit to be used as a heater.

[colan]

What are the errors?

How do you have the Multiplus wired into the system? Are you using a sub panel?

Hate to ask this question, any chance the thermostat is set to cool?

[JohnD]

I am not using a subpanel. Line 1 from shore power drives the AC input to the Multiplus. The Multiplus AC Output 1 goes to a Bomain switch and gets patched to line 1 of the breaker panel. The Bomain switch allows me to manually select 50 amp service (line 2 from shore passed to line 2 in breaker panel), vs 30 amp or less (Multiplus AC Output 1 to line 2 of breaker panel, so AC Output 1 energizing both lines of the panel - in phase obviously and at reduced current capacity).

The alerts are I'm receiving are indicating "assist mode", "battery low", and possibly something else, but I can't remember. I also hear/see the Multiplus kick in and hum during these intermittent periods. Just to repeat, nothing is on as far as I know on the AC breaker.

If some of my answers seem ambiguous, it is because my slide is broken and the thermostat and breaker panel are barely visible with the slide closed. I dropped it off for service today and hopefully get it back this evening. My Air Conditioner is wired to line 1 of the breaker panel (though I have not completely confirmed this because two breakers are labeled AC, and I currently only have one unit. I don't think the thermostat was set to cool, but it is a possibility. Even so, why would an AC unit draw current every 30 seconds or so when it is 30 degrees out?

[Country Campers]

The thermostat is used for both heating and air conditioning. If the thermostat is set to "Auto Fan" , if my memory is correct , the a/c fan may kick on during furnace operation. When heating I keep the fan selection to "High" , this keeps the a/c fan from coming on. This may be the total opposite so please correct me if wrong. It may be possible that the Multiplus is seeing some kind of signal from the thermostat to the a/c.

Brian

[ncitro]

JohnD

Thats a strange one. Even if it was as Brian suggested and the fan was trying to run, your shore power should handle that draw without trying to kick in the MultiPlus with no issue. To be honest I have run my AC unit off of the MultiPlus with no Easy Start just as a test and it ran fine with no errors. What shore power are you connected to when this happens? 30 Amp or 50? What do you have the input power set to on the MultiPlus? Do you have this problem when connected to both of those? If the problem goes away when the breaker is off, then there must be something in the AC causing the Multiplus to load down.

[openrangeowners]

EasyStart_Advanced_Troubleshooting.pdf

check the trouble shooting section where they mention unexpected current - something to do with the learn process where you run the AC for 5 starts ...

[howson]

I'm doing a solar install and have found that my Victron Multiplus keeps surging and throwing errors intermittently. I've tracked it down to the AC breaker. With the AC breaker off (its 30 degrees, so it shouldn't be running anyway), the problem disappears. So, I'm wondering if anybody has experienced something like this. Why would an AC unit have a power spike intermittently when its 30 degrees outside and presumably off? I have recently installed an easy start, but hadn't experienced any issues prior to the solar/battery install.

John--not sure if what I experienced will help, but the full story about a firmware issue in the EasyStart is here: https://gdrvowners.com/forum/operati...ir-conditioner

[JohnD]

Thank you everybody for the great input. Unfortunately I've been on a wild goose chase. I just got the RV back and the slide is fixed so now I can actually access the electrical panel. Further inspection shows that the panel is mis-labeled and/or mis-wired. The rightmost 20 amp slim breaker is the A/C, and the 15 amp slim breaker next to it is the refrigerator and the receptacles below the dinette (and possibly others). The one labeled refrigerator is the microwave, etc. The offending breaker is the slim breaker labeled A/C that is wired to the refrigerator and receptacles. So, tomorrow I'll actually open up the panel to figure out the true wiring and make corrections as necessary. I'm pretty certain they did not intend the refrigerator to share a breaker with other receptacles. I suspect there is some sort of loose connection or nicked wire that may be causing the intermittent power surge. We shall see.

[howson]

I'm pretty certain they did not intend the refrigerator to share a breaker with other receptacles.

I wouldn't be that certain...here's how mine is actually wired. (The colors and numbers correspond from the item to the power box in the diagram if that's not obvious.) The refrigerator is on a circuit with a *lot* of other outlets in the living area (yellow 3). It's the outlet that looks like it is "outside" (since it is only accessible from the exterior by taking off the lower refrigerator vent.

[openrangeowners]

Good - the eliminates an issue with the AC. Looks like the Refrigerator or Microwave circuits are your issue. If they are both in a slide, check the wiring under the slide where it runs to make sure it is not partially cut or damaged. I would definitely start there first.

Second - check to isolate to either the fridge (easy to troubleshoot because you can unplug the fridge from the outside panel access - also may have other receptacles in the kitchen tied to this ...) or the microwave - again you can unplug the microwave to troubleshoot .... this will help to determine if the actual appliance is the issue or the wiring to the appliance (or other receptacles wired on the circuit).

My guess is that you will eventually find a receptacle that has the wiring not properly attached or a screw that has partially gone through the wiring insulation causing an intermittent connection between ground/neutral or power/ground or less likely neutral/power (this should tip a breaker).

Do you have a Fireplace? If so that circuit could be an issue - can also unplug to isolate it from the actual wiring.

Let us know what you find. I see the issue with the labeling .... now I see how to read it

[JohnD]

Okay, so interesting findings here. The refrigerator does share a circuit with other receptacles and the refrigerator was not the issue. It turns out to be an issue with a Brother printer. We have now tried two different printer with the same results. I've also moved the printer to a separate circuit from the refrigerator and same results. The Multiplus starts assisting when the printer is powered on, and then I get a battery low and overload alert. One time the Multiplus went into Fault, and I had to manually turn it off and back on. As part of the test, I turned on an instapot, portable heater, and AC unit, drawing 3300 w from the inverter on battery only, and got an overload, but no fault.

Anybody else had issues with Multiplus and a printer?

[openrangeowners]

My 2 brother laser printers have destroyed 2 UPS ... they produce spikes of AC power that make the lights flicker. As printers they are awesome and have lasted 7 years so far. If it runs out of paper it continues to energize as if printing once every 20-30 seconds until you fill the paper tray.

https://help.brother-usa.com/app/ans...erter%3F-can-i