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DuoTherm A/C main 120 shorted Now not much working


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I have a 2003 Gulfstream DP. After a day at Colonial Williamsburg with the grandkids we came back to the RV where it was 94 degrees inside. I found the breaker to the front A/C tripped. So I reset it and still no front A/C. After looking for a few minutes I determined I needed to call for help. A mobile RV tech came and found that the main siring to the A/C was shorted out. Even with both breakers in the RV shut off there was still power to the A/C wiring due to the short. Once I shut off the breaker at the pedestal the wiring short was fixed and we thought all should be well. Not so fast says the RV. Now there seems to be little power going to anything with shore power. Te main breaker panel has full power but it no electricity seems to be going anywhere. The inverter has A/C going in but nothing going out. If we start the generator some 120V stuff works but not everything. To make some of the 120 receptacles work I can hit the invert button on the remote control for the inverter and some 120 outlet work.

The inverter is a Freedom 458.

Some of the symptoms:-


Shore power

No 120 in the coach.- Checked for thrown GFI's

No inverter - will check for internal fuse in a little while

No charging of the batteries

The fridge only works on gas


With the genset:

Batteries are not charging

The fridge only works on gas.

partial 120 v receptacles work

If I hit invert on the remote panel for the inverter

Different 120 receptacles work

Rear A/C work


Now that the batteries are low none of the items mentioned work anymore.


I'm looking for an mobile RV tech that has electrical knowledge.My brain thinks it funky how some stuff works and not other and some options are:

neutral is open,

inverter got fried,


Any one with any ideas would be greatly appreciated. Suppose to take the grandkids to WV to the CASS railroad statepark tomorrow before heading back to Florida.


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Once I shut off the breaker at the pedestal the wiring short was fixed and we thought all should be well. Not so fast says the RV. Now there seems to be little power going to anything with shore power.

Assuming that you do not have the generator or inverter operating, this is exactly what should happen. The circuit breaker at the pedestal open means no power through the shore power cord.


To make some of the 120 receptacles work I can hit the invert button on the remote control for the inverter and some 120 outlet work.

This is probably normal since most RV inverters are wired to only supply power to selected outlets or loads.


Shore power

No 120 in the coach.- Checked for thrown GFI's

If you still have the circuit breaker on the pedestal open and no generator running, that is exactly what should happen.


The fridge only works on gas

This tells me that it not only has propane but it also has 12V-dc, since the controls work from 12V power. If you have lights, those also get power from 12V. That same is true of the water pump. But if you do not have 120V to supply the converter/inverter you will run down the batteries before too long and those appliances will stop working. Of particular importance is your refrigerator as it will not cool on propane without 12V power.


If I hit invert on the remote panel for the inverter............... Different 120 receptacles work

That is normal since the inverter probably only supplies some outlets, but using the inverter will quickly drain your batteries.


Rear A/C work

Am understanding correctly that the rear A/C works if the generator is running but not from shore power?


Before you go too far, this may not be needed, but when you were checking the circuit breakers, did you open and then close each one? A circuit breaker is designed such that it must be fully opened in order to reset and with many you can't tell for sure just by looking at them if they have tripped. When I check them I always run a finger down along the surfaces first, looking for one which feels slightly out of line and check it first by opening it, the closing it again. In your case, I suggest that you do this with every circuit breaker since you are not sure and clearly are confused. There should be one main circuit breaker that is larger which removes all power from the distribution panel. It will be rated at 30A if you have a 30A power cord or at 50A if yours is a 50A power cord. In some cases the genset also supplies power via that main breaker but not in all cases. If you have a 30A cord and a larger generator with two roof air conditioners, then you might have a main that only supplies one a/c and the rear only gets power from the genset and not from shore power, which may be the reason that it will operate with the genset running.


If you read this before you call for help, do the circuit breaker check first, then reconnect shore power and close the pedestal circuit breaker and test to see what does and does not work. In more than 40 years of electrical work, I have never seen circuit breakers short in any RV or other installation so I suspect that your tech didn't know what he was doing.

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Probably need to explain some of the symptoms better.

With 120v at the pedestal I have voltage at all of the breakers in the main panel. In the main panel there is an orange romax going to the inverter. The AC in on the inverter has 120v, but the AC out has none.


With the shore power unplugged and the inverter on, most of the 120v outlets do work. I believe they stopped working due to low batteries. I bought a charger and manually charging the house batteries.


With shore power connected I have

All of the breakers have power, but nothing is working. The inverter lights are all off.

The orange romax to the invterter in still has power, but nothing on AC out.


With the shore power unplugged and the genset running I have

power to everything that is fed from the main panel box.

No power to the outlets or microwave since they are ran from the AC out from the inverter to the second power panel.

I disconnected the front A/C since that was where the original issue was at. But there is power to the wiring.


The big difference is that with shore power no A/C.

I found a blown fuse on the fridge on the 120v side, so that may be why the fridge won't run on power. Need to get fuses.


More to come with further investigation.

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1) Check for a reset button on the invertor. Mine is hidden away and you need a mirror to see it...

2) Check the main fuse from the battery back into the inverter. It will be a LARGE one just before the 12V gets to the inverter.

3) Check the transfer switch wiring to make sure it is tight and everything works as it should at that point.

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More update

The reset button is reset, no joy.

The main fuse checked okay

Found blown fuse inside the inverter on the board. Going to go pickup fuse for inverter and fridge.

I still need to check the transfer switch wiring.

Thanks again for the tips

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Just got back from traveling to 8 stores trying to find fuses for the inverter and fridge. Once the fuses were located we traveled the 35 miles back to the campground to hopefully fix the remaining issues.

Once the fridge fuse was replaced it started running on A/C.

Not so lucky with the inverter.

Replaced the little .25A fuse to no avail

The inverter still doesn't charge, nor does it have A/C out voltage. So no items from the second panel operate.


I still need to check the transfer switch to see why I have no shore power items running.

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There are several different ways that an inverter can be connected so it might help to know what make & model your inverter is.


I still need to check the transfer switch to see why I have no shore power items running.

I don't get this remark? You just said that the refrigerator now operates on 120V-ac. If that isn't shore power and your inverter isn't working, where is that 120V-ac coming from?


The transfer switch is a device which selects between the genset and shore power for 120V power. If you can get power from the generator, that says that it is switching as the relay shifts when the genset begins to supply 120V, whether you have shore power or not. (You should always shut off all major loads before starting the genset.) The typical connections are to have one input to the ATS that comes from shore power and a second one from the genset, and the device selects between the two. The only 120V power which does not pass through the ATS is that from the inverter.


When you state that you have power at all of the circuit breakers, do you mean that you have taken the cover off of the distribution box and verified with a meter that there is power to them? If so, then have you also verified power out of them to the circuits that they supply? One of those circuit breakers is the supply to the 120V heating element in your refrigerator, which you report to be working.


I really don't think that I fully understand what you are telling us.

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While checking voltages it appears that there is power coming onto the coach from Shore power as well as generator. What appears to be happening is that the inverter is not detecting 120 volts from either the pedestal or the generator. The only way to get the 120v to work is to have the inverter invert to 120v. I never had to do this before so it is very confusing.


When on shore power the coach still has no 120v. Acts like an open circuit somewhere.

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Sorry for the confusion on the explanations. As soon as I think I see what's going on I find that I still have problems.

The genset is on and the fridge will run on that power as the breaker is in the main panel. But, most all other items are in the second panel that goes through the inverter.


Now that you ask the question about the power getting to the outlets that the breaks are supporting I am checking the output side of the breakers, but not the wiring at the other end. I will check those and report back..


I finally spoke to Xantrex folks and it does appear that the passthrough portion of the inverter, along with the charger, is bad due to the shorted wiring from the A/C.


As Kirk mentioned I still need to check for power at the A/C's and outlets from the main panel.


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Just as a sent the last response I was thinking: How can there be an open circuit from the shore power to the A/C and other outlets from the main panel when these items are working on the genset?

I'm glad I'm on vacation and don't have to think :):lol: , becuase after 2 days of this my brain hurts.

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Your coach is wired so that the outlets are powered from and through the inverter. If the inverter is not working properly you will have what you experienced. There are much better inverters out there. I upgraded to a Magnum inverter. They also have a hybrid inverter that will add power from 12 volts if the pedestal has low power. Now may be the time to review your needs and rework your system to work the way you want it to.

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It does sound like a problem with the inverter. I'm guessing that you have a sub-panel distribution box that is fed from the inverter. It should have an input for 120V-ac that comes from the main distribution panel which in turn gets power from the transfer switch and either shore power or the genset, depending upon what is in use. The properly working inverter then would detect that 120V supply and pass it through to the sub-panel to the loads that can be supplied from the inverter when no 120V supply is available. It would appear that the detection system has failed and from what you say, it also doesn't charge the batteries or supply 12V-dc as it should when 120V is available. Since there was a fuse blown, most likely that happened when the inverter failed and it has more than that wrong.


One thing which really bothers me is the idea of a shorted a/c unit While that is possible, it is highly unlikely but there are plenty of possible problems in an a/c that could cause it to draw excessive current. Even so, if/when that happens the circuit breaker on your 120V distribution panel should open and so protect the system and I can't see any reason for the excessive load of the a/c, even if shorted, to cause the inverter to fail. I strongly suspect that your mobile RV tech is not well qualified on a/c units, which would not be especially unusual. If it were me, I'd get another opinion on that a/c before I went further with this. As long as you keep the circuit breaker for it open, there should be no problem for other parts of the RV. Should you want to trouble shoot the a/c and not risk anything else, just open all of the other circuit breakers before you close the one supplying the a/c in question.

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First thing is to follow every connection of wire in the system in a particular power mode. They would be at the transfer switch, electric panel and then the outgoing wires at the inverter.Then your inverter may need to have a hard reset done on the unit.

You may have two different problems that are making it frustrating to solve.


Safe Travels, Vern

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Good Morning to all.

The short at the A/C was the main wiring powering the A/C unit. Somewhere in a prior life someone put a junction box in and the wiring was wedged between the frame of the A/C and the junction box. The wiring actually shorted and caught fire as he was looking for the problem.

Even though I had both breakers in the coach off there was still power due to the short. I believe the extra issue was due to the power back feeding before I was able to unplug the shore power.


Since I believe that the inverter is bad and not charging the batteries that I might as well just bypass the inverter and connect the A/C in and the A/C out at the inverter until I can replace it. I am seriously thinking on a pure sine wave replacement.


I just bought replacement batteries and now will need to verify that the transfer switch is working properly.


More to come

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Another update now that we are back in civilization where there is wi-fi and phone service. Back woods West Virginia not so much. Very cool is the Cass Railroad State Park, but you are out there.

It seems that the A/C short was a symptom of the main problem but not the main cause as some have replied. I replaced the house batteries just in case they were taken out in the may lay. When we arrived at the campground we were staying at I plugged into the shore power. Some outlets and things worked, but a phone charger and surge protector went up in smoke. So I unhooked the shore power and used genset. The Progressive protector or the transfer switch may be the culprit and I will hopefully know tomorrow when an RV tech comes by and takes a look see.

Everthing seems to work on genset so I am going to assume ( ass U me) <_< that the rest of the wiring is good.


I'll give an update as to what the RV tech thinks after he's had a look.

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It is very difficult to make any technical advice without being there to make some meter readings and do in person trouble shooting. I hope that you get a tech who has a strong electrical background as that isn't always true. I would love to do some investigation in person as your postings have left me with more questions than answers.


Keep us posted, please.

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Hello to all that have been helping out and sending replies.

Now for the rest of the story. When thge RV tech came this morning everything worked on shore power, at first!

After a few minutes different outlets and equipment would stop working.

When the tech first came he checked all of the voltages and all was well. After about 10 minutes and buttoning things up is when stuff started to happen.

Getting to the point is that the Progressive Protector wasn't protecting very much. It would start out at the normal voltage and then something would happen and it started putting 160v on one leg and 80v on the other. The tech actually saw a spark on the neutral as I was turning things on when it was 120v on both legs. Tech removed the progressive unit and all is well, except for the things that didn't like the high voltage. Inverter, microwave, and numerous fuses for the fridge.


Looking back this is probably the cause of the A/C overload and the A/C wiring fire. Also, since it was intermittent it was making me go batty trying to troubleshoot.

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