Fuse Panel miss marked - need help

[fredwrichardson]

Well I am trying to trouble shoot a DC electrical problem. My fuse 14 in the panel seems to blow when the EMS tries and shed one of the ACs. My problem is the panel says fuse 14 is rear wall and LP. Well when the fuse blows two of the thermostats lose power and also the fantastic fan in the bathroom stops working. Nothing to do with LP or the back wall. I have attached the fuse box label so you can see what it says the fuse is connected to. Fuse 13 says Refer but I have a residential refer and when I pull the fuse the refer works fine (thought it might be the inverter but it is not). Fuse 17 says Yetti but I do not have the Yetti package. I think they mis labelled my fuse box but not sure where to got to get the right info. I have a 2015 Ashland with three AC, no Yetti, two awnings, residential refer with inverter. If anyone has a similar RV could you look at your fuse panel cover (label is on back) and tell me what is what with the fuses.

Thanks

 

[wdk450]

I would think that the EMS would only be connected to the AC (Alternating Current) electrical system, and would not affect the DC electrical system. The only component common to both power systems is the Power Converter/Battery Charger. As to why your DC fuse is blowing concurrent with the EMS function, I haven't a clue. Maybe the EMS vendor might have an idea. Their phone number might be on the vendors list on the left side of the forum Portal page.

I would Call Heartland Service with your VIN number whenever they are open after the holiday weekend. They should have a wiring diagram (that they usually don't share due to corporate policy), and a correct fuse label data for your unit. They should be able to generate you a new fuse label. I think that this is an electrical safety issue by Electrical Code, and they should sen you a correct label.

 

[Silverado23]

You need to pull all of the fuses and add back each circuit testing all the devices on each until you know everything is working.

You could do this in two stages and test as you pull and remove the fuse and then when all the fuses are removed confirm that you have the correct devices as tested.

It is time consuming but as least then if you have a wiring issue you would know and not find out later down the road with something else.


Make sure you know what value fuse you have/need for each circuit.

 

[fredwrichardson]

Bill,

All of the Air Conditioner circuits that deal with the EMS are DC and not AC. Found that out by testing how the A/C compressors are turned on by the thermostats and all that is DC and they use DC relays. That is why it is so important to understand what is on the DC panel. Looks like they do multiple devices on the same fuse like two thermostats and the fantastic fan all on the same circuit plus whatever. Was trying to avoid having to go through each circuit but that will be my task tomorrow.

 

[Silverado23]

A couple of other options that you could try is calling Heartland Customer service with your VIN. I wonder if they would have a list of the circuits for your unit.

The other possibility is to pull the panel and see if the wiring is labeled. When I had pulled my panel last month, I noticed a number of the cables in my RV were labeled with marker to indicate which circuit it belonged.

 

[wdk450]

Bill,

All of the Air Conditioner circuits that deal with the EMS are DC and not AC. Found that out by testing how the A/C compressors are turned on by the thermostats and all that is DC and they use DC relays. That is why it is so important to understand what is on the DC panel. Looks like they do multiple devices on the same fuse like two thermostats and the fantastic fan all on the same circuit plus whatever. Was trying to avoid having to go through each circuit but that will be my task tomorrow.

I forgot the thermostat circuits. I should have remembered that as I did the digital Hunter Thermostat upgrade. I would expect the 12 volt DC thermostat to drive a relay that energizes the alternating current air conditioning (too many "AC" terms in that sentence). But relays are sort of an isolation device. One circuit switches another with only a magnetic coupling. Maybe some bare wires just touching at the control relay's base from the mechanical shock of the air conditioner starting up? So the Air conditioner control box might be a strong suspect for your problem.

I'm trying to help from my many years of electrical/electronic experience, but I have to admit I am unfamiliar with the type of RV EMS that shuts down electrical loads.

 

[danemayer]

Bill,

The Precision Circuits Power Control System has additional components at the circuit breaker panel. To shed the A/C load, it fires a 12V relay that interrupts 110V AC power to the air conditioner.

 

[fredwrichardson]

I forgot the thermostat circuits. I should have remembered that as I did the digital Hunter Thermostat upgrade. I would expect the 12 volt DC thermostat to drive a relay that energizes the alternating current air conditioning (too many "AC" terms in that sentence). But relays are sort of an isolation device. One circuit switches another with only a magnetic coupling. Maybe some bare wires just touching at the control relay's base from the mechanical shock of the air conditioner starting up? So the Air conditioner control box might be a strong suspect for your problem.

I'm trying to help from my many years of electrical/electronic experience, but I have to admit I am unfamiliar with the type of RV EMS that shuts down electrical loads.

Well today I went through every DC circuit. Only three circuits were marked correctly. The majority were not even close. Now back to my troubleshooting. It turns out that fuse 17 that says "Yeti" on it is not even used so I took the two connections on fuse 14 (the one that blow when EMS starts shedding ACs) and used fuse 17 for one of the connection. In effect separating the two connects. Turns out that one wire has at least two thermostats and the fantastic fan on it. The other looks to have just the hallways lights and the W/D closet light. When all the lights are off the circuit is open so there is nothing else there. I ran two ACs on 30 amps and let the EMS do its thing. Well it did not blow a fuse so there is promise but last time it took 5 days before it blew. I do believe that the EMS relay is on the same circuit as the thermostats and fantastic fan. The connector on fuse 14 did have some extra insulation in the connector so the crimp was not that great and could be part of the issue. We will see for my wife and I are are going to California for a funeral and will be gone Monday through Friday. On this trip going to run on 30 amps to stress the EMS and see if the problem comes back.

 

[fredwrichardson]

Well today I went through every DC circuit. Only three circuits were marked correctly. The majority were not even close. Now back to my troubleshooting. It turns out that fuse 17 that says "Yeti" on it is not even used so I took the two connections on fuse 14 (the one that blow when EMS starts shedding ACs) and used fuse 17 for one of the connection. In effect separating the two connects. Turns out that one wire has at least two thermostats and the fantastic fan on it. The other looks to have just the hallways lights and the W/D closet light. When all the lights are off the circuit is open so there is nothing else there. I ran two ACs on 30 amps and let the EMS do its thing. Well it did not blow a fuse so there is promise but last time it took 5 days before it blew. I do believe that the EMS relay is on the same circuit as the thermostats and fantastic fan. The connector on fuse 14 did have some extra insulation in the connector so the crimp was not that great and could be part of the issue. We will see for my wife and I are are going to California for a funeral and will be gone Monday through Friday. On this trip going to run on 30 amps to stress the EMS and see if the problem comes back.

Just got back from our trip to California. When on a 30 amp hookup and both middle and upfront A/Cs are turned on and the EMS starts to shed things and then starts to un shed the second A/C the 12 volt fuse (position 17) blew. This is the same fuse that the bedroom and up front A/Cs thermostats are connected to including the fantastic fan. I assume it is also for the 12 volt relay or relays that are connected to for theses A/Cs. Next step is to trance the #17 fuse line and see how the EMS is connected to it. What is interesting is the EMS sheds a A/C by applying power to the relay to open the circuit to the thermostat. That seems to be working fine. When the EMS un sheds it removes power to the relay causing the relay to close and that blows the fuse.

 

[danemayer]

Fred,

I'm going to guess that the driver transistor on the Precision Circuits control board has a problem that's shorting the 12V circuit when it de-energizes.

Might also be the relay itself, but that seems to me to be less likely.

I'd call Heartland and see if they can get you a replacement circuit board. Or perhaps a call to Precision Circuits would be an easier and quick path to getting a board. And if you can get one of their engineers on the line, they might be able to confirm whether the board is the likely failure point. 630-240-9832

 

[fredwrichardson]

Fred,

I'm going to guess that the driver transistor on the Precision Circuits control board has a problem that's shorting the 12V circuit when it de-energizes.

Might also be the relay itself, but that seems to me to be less likely.

I'd call Heartland and see if they can get you a replacement circuit board. Or perhaps a call to Precision Circuits would be an easier and quick path to getting a board. And if you can get one of their engineers on the line, they might be able to confirm whether the board is the likely failure point. 630-240-9832

Dan - Appreciate the insight. I will call Precision Circuits on Monday.

Thanks.

 

[jb007]

Have any idea what 15 is? it says fan's, there is a wire coiled up in the island that has 12vdc, it is on this fuse, when I pulled the fuse no voltage on wire everything else still worked.

 

[billyjoeraybob]

Dan - Appreciate the insight. I will call Precision Circuits on Monday.

Thanks.

Fred,

Did you ever determine the root cause of your issue?