Blown fuses

[tervio]

I have visited this site several times and have enjoyed the info that Sunline owners have offered. I now find myself in need of some of that expertise. I have a '04 2363, and did take the unit in for the Dometic re-call and have used the trailer 2 times since. I ran into a problem this weekend and was wondering if anyone can help. I had the unit under AC power overnight and Sat. morning switched over to gas. I saw the unit ignite so I thought everything would be okay. When my wife and I arrived to our site we noticed that the 15 amp fuse was blown which shows ref/bath on the fuse panel. The fuse seems to blow when trying to go to gas mode. We had no AC power at the site so I could not check to see if the fridge still work on AC power. Any ideas?? I did disable everything in the bathroom and the fuse would still pop.

Thanks

[JohnB]

Hi tervio

Let me see if I can help.

See this pic. Do not mind all the meters and stuff, that was the only pic I had loaded on the web with the fridge panel off and the 120 VAC cord in the shot



Take the panel off and pull out the black normal looking plug. That is the 120VAC to the fridge. Then reset your breaker. Power up the camper, does it trip?

This will isolate down it is or is not the fridge. Before you go nuts looking at the fridge it might be elsewhere.

While you have the panel off look for any wires that are nicked or bare touching any of that new sheet metal they added for the recall.

The main fridge runs on 12 VDC including the gas portion and the igniter for the propane. The only 120VAC is the actual electric element.

But you said it “seems” to trip on propane.

Question: While the breakers did trip, did the fridge light inside the fridge still work, or the little orange lights on top still on? They all run off 12 VDC, even though the breaker tripped they should stay on. Or you have other things going on we have to drill down into.

Hope this helps

John

[tervio]

At the time we did not have any AC power at our site. I even had all the AC breakers switched off. The fuse that would pop was a 15 amp with ref/bath on the fuse panel door. The fuse would blow when I turned the ref. on
Thanks for your help
Terry

[JohnB]

OK you mean the 15 amp, 12 volt DC fuse….. Nothing to do with the 120 VAC circuit breakers…

OK your 2004 model convertor looks like one of these 2.

The CS6000XL


Or the CS6000


The 2004 model TT’s made in later 2003 had the CS6000 and the ones in early to mid 2004 had CS600XL. Lucky me I happened to get one of each….



Since this is the 12 VDC DC fuse feeding the bath and fridge…..well this changes things.

If the unit actually runs on 120 volt electric and pops that 15 amp fuse on propane, I “suspect” that the igniter or actual gas valve wiring may be pinched by the new recall shielding creating a short when the unit fires the ignition sequence. The igniter and the gas valve only work when the unit is on propane. The rest of the unit controls works both 120VAC and propane.

If that fuse is labeled bath/fridge, then the lights/exhaust fan in the bath would be on it as well. With the fridge turned OFF, does the bath fan and lights work OK. If so and no fuse blow, then yes I would say the gas portion of the fridge wiring may be suspect or at least a place to start.

Take a look and let us know

See here for the wiring BEFORE the recall shield was added.


The yellow wires are the 12 volt hot to the gas valve and the little silver looking one is the igniter wire. Look for a pinch on those wires.

Hope this helps

John

[tervio]

I did get out to the trailer and did find out when fuse would blow. I had 2 items disconnected, the gas valve and the thermo fuse. When I put the wires back from the gas valve nothing, but when I put 1 wire on the thermo fuse that is when the 15 amp DC fuse would blow. I think it is the thermo fuse it is connected to the round metal tube by two sheet metal screws, it has 2 wires going to it but it would blow the fuse when I tried to put 1 wire back on. Does this thermo fuse go bad? if so does anyone know why and is this causing my problem?

Thanks for your help

[JohnB]

Hi tervio

See this link on the RV.net tech forum.

http://www.rv.net/forum/index.cfm/fu.../1/page/70.cfm

It should go to page 70 of that Dometic recall post.

It does seem that some have had problems from the recall when the thermo fuse was installed too close to the burner. It melts the fuse.

There is a pic of it there as well.

Is this the part you are referring to


OR are you referring to this part with the 2 red wires and the 2 sheet metal screws. That is a thermal disk switch.


If you pull the wire off that switch or the fuse, it drops out the gas and electric element on safety. So pulling the wire off stops the unit from working. This may explain why your fuse does not blow with the wire off as nothing is working but may not explain what is touching ground (bare metal) causing the fuse to blow.

Check the thermo fuse if it melted to touch metal. It sounds like “maybe” the recall had an installation issue in your case.

Hope this helps.

John

[tervio]

John
Thanks,it is the thermo disc which is the unit I took the two red wires off. Also like you stated with the wires off nothing is workink on the ref. Does the disc go bad? with replacing the disc will that correct the problem or is there other bare or cut wires I should be looking for?

Thanks
Tervio

[JohnB]

Tervio

The thermal disk switch, aka Klixon switch, normally do not short to ground, but may. That little red button in the center is a reset if the switch trips. There are a few brands out there that have this technology. http://www.klixon.com/products/contr...herm-20600.htm The switch warms up and the disk inside flexes and opens up the circuit

Do you have an ohm meter or a continuity tester?

By unplugging the thermal disk switch the unit will not work and it will/ may not short out either since they can wire that saftey circuit in the J4 pin which is 12 VDC feed circuit to the PC board.

Check the wiring, 12 VDC comes to a teraminal strip, then to the thermo disk switch, then out of the disk switch to a thermo fuse under shrink tubing then back to J4 pin on the control board. Not all are wired this way but some. I can't tell how yours is, that is the most likely method.

It sounds like you have a short to ground, most likely a wire touching metal thru the wire insulation. With the power and battery off, you can take the 12 VDC wiring off 1 at a time and check to ground for a short. One end of the tester on ground the next trouble shooting each wire path. But you have to unhook some items to test so you do not get a feed back like thru a gas valve coil or the circuit board

Try this if you do not have a tester. Un plug camper from shore power, turn battery disconnect off or unhook battery.

Fell and trace each 12 VDC wire along it’s full length at the fridge back area. The 2 gas valve wires, the new recall safety circuit wires leading to that thermo disk switch\ and the shrink tube thermo fuse. Those are the likely ones I would start at. If they prove out OK report back as this get’s a lot deeper.

If you have a meter and know how to use it, let me know I’ll go thru that in more detail.

John

[Indy-Jim]

John - your evaluation and suggestions regarding the problem are very enlightening. Unfortunately, most Sunliners (including myself) have no clue as to what the modification consists of, etc. unless one digs into the system after the mod has been installed. I believe that Domentic should provide the user with data that explains the mod regarding why it is required, what the modification does and a description of any installed parts/wiring that is included.
This topic is interesting to me as we checked in at the Scenic View Family Campground located 6 miles Southeast of Logan, Ohio last Monday (20 Oct) and to our surprise, there was a Sunline coach a few campsites away. Upon meeting these folks, we learned that they were from Pittsburg, Pa and were proud owners of an "05 T2363. Unfortunately, they just had the mod installed in their fridge prior to leaving on their trip and when they got to the campground, they found out that their fridge did not work. A minor evaluation of the problem indicated no operation whatsoever. Checking things out, there was 120VAC at the fridge plug, there was 12VDC at the terminal block that feeds the fridge, however, when the fridge on/off switch was pressed in, no indicator lighting was evident at any time, nor did the fridge start up. All indications were that the mod installation process affected something beyond the mod itself. We felt it best to not go any farther with troubleshooting at that point since is should be the responsibility of the installing dealer to correct the problem, whatever it might be. I did ask the owner if the installer had checked out operation after installing the mod, and he said no. BIG MISTAKE!I felt sad for the owners since they had this problem, probably on their last trip of the season, and could not use their fridge. However, it was good to see another Sunliner in the campground.
On a side note, last Wednesday when we got up in the morning, it was 24 degrees. Needless to say, our water hose was frozen solid.
Jim

[JohnB]

Jim

WOW… 1st off you where very close to driving past our stomping ground on your way over from Indy and down to Logan. We do camp at Hocking Hills area often. Assuming you came over I70, the I270 around Columbus and down Rt 33. If you ever get back over this way, let me know.

Gee another Sunliner in Ohio….Cool!!! And a newer TT. We see several of the older Tan ones, still going strong. But we ever rarely see the newer white ones, not alone a 2005.


For Jim and Trevio

Now to the recall, here is my knowing of the topic. The problem is result of concentrated heat in one area and repetitive thermal expansion of the boiler tube that over time may form a crack. The crack lets the ammonia out of the coil and if an open flame is present at that time it might cause a fire. All the stars have to line up for this to occur, but has in some cases.

The thermal expansion issue comes from the electric element from what I have learned by the element doing 1 of 2 things or both. 1. The wattage of the 120 VAC element is too high, it over heats the boiler tube, creates a high stress and then over time it may crack. 2. The actual element has a concentrated heat zone at the tip creating real hot spot causing a thermal expansion issue over time. Or both occurring at the same time. That is the problem as I know it. I’m not a Dometic expert and do not claim to be one but this is the trail that I came too. Others may have different views.

The recall addresses the safety aspect of the problem. Meaning that if a possible fire is about to occur or occuring there is nothing to shut the system down. So they created the recall kit.

There are a few ways but this is the most popular I hve seen. They tap into the 12 VC power line that feeds the control board. If this 12 VDC is not present it will shut down the gas and the 120 VAC electric heating element and the entire PC board inclusing the ignigtor.

They added a thermo disk switch, with reset button to the side of the round sheet metal housing. That little button in the middle is a reset if the switch trips OR if it was never reset from day one. Your camping buddy may have not had the switch reset. A push of that button may have got him going. The disk switch has the 2 red wires going to it.

They also added a thermo fuse in series with that thermal disk switch. It is a small diode looking device under black shrink wrap tubing.

See pic


Here is a pic of one of the recall wiring diags


By the way those recall pics are not from my camper. There are from a fellow camper up in Canada. I just drew on them to help show the points I'm typing.

What this does is if the heating systems get out of control or over heats and the sheet metal gets real hot, it trips the thermo disk switch and shuts down both gas and 120 VAC electric elements etc. The Thermal fuse is an additional safety that if the area gets too hot it melts the fuse and then it shuts down the system. There has been noted in some cases the thermal fuse is too close to a tube that gets hot and melts the fuse by accident. See the RV net links for that above.

The added sheet metal is to contain the heated area to not spread to the coach.

Now what did it look like before the recall. See here on my camper. Don’t mind the meter and unhooked wires. I was checking the resistance of the 120 VAC element to make sure I did not have one that had high wattage. See the 12 VDC terminal block.


Now out of that terminal block is a red wire that goes to the J4 pin on the control board. This is the main 12 VDC feed to the PC board. The recall took that short red wire off the terminal block and replaced it with a long one that went to the thermo fuse then in series to thermal disk switch and then back to the J4 PC board. This is how many of them are wired up. Not all, but many. Some tap into the P1 terminal pins. I have not seen one of those but the diagrams show them



The recall addressed the fire safety issue. It does not address the problem of the thermal expansion that causes the cracks in the boiler tube. Looking for thermal metal fatigue that has not yet broke is hard to do with out a lot of fancy equipment looking at the surface of the metal and even then a good metallurgical sample needs to look at the grain structure of the metal after a crack to declare it thermal fatigue. So now what….

Well for me I checked the wattage of the heating element to make sure it was within tolerance. If it was out I would of replaced it. Get the recall done, understand what it is they are doing and hope I’m not one of the statistics with the issues. If you have the issue, the damage is already done and time will only tell how long the unit will last. The recall at least addresses the safety problem. I know this does not leave us with a lot of warm and fuzzy feelings but this is what it is, again from what I have learned and investigated. Again others may have more info as I never yet heard and official response from Dometic on the exact root cause that started all this.

Hope this helps

John

[BobNKaren]

I had a problem with a different fuse blowing it was a fuse that supplied the propane dector and some lights. Prior to the fuses going I noticed the one light dimming and go back to normal. The second time that this happened I checked the fuse prongs and noticed that they where burned. I was able to switch the circuit to an unused fuse holder in the distribution block and that solved the problem. The arching in the holder was causing the fuse to open.

A lot of electrical problems go un solved because of poor grounds. When ever I am tracking down problems I use a long wire connected directly to the negative post of the house battery to my meter. Then I check both the supply + side and the return side – at the item I am checking. You would be surprised at the return loss to the battery. A buddy of mine had problems with his furnace and it turned out to a poor ground, He had a loss of almost 2 volts on the ground side. The quick fix was to put a quick jumper directly to the battery ground side. When we got back home, a trace of the grounding point we found the crimp connector corroded. The rig was only 2 years old.

[tervio]

Thanks for all the suggestions, I'm not sure when I will be able to get out to the trailer but now know what to look for. I will post what I have found.
Thanks again

Tervio

[tervio]

I was able to get out to the trailer this weekend. I'm not sure what was the problem but after checking for sliced wire, short to ground, etc. the only thing that I did notice was a couple of the push on connectors were not pushed on all the way. (maybe during transport or something). The ref. worked on both AC and LP.

Thanks for all the help
Tervio

[JohnB]

Originally Posted by tervio

I was able to get out to the trailer this weekend. I'm not sure what was the problem but after checking for sliced wire, short to ground, etc. the only thing that I did notice was a couple of the push on connectors were not pushed on all the way. (maybe during transport or something). The ref. worked on both AC and LP.

Thanks for all the help
Tervio

Glad it was that simple. Good.

But this was educational along the way as I did not realize many others had problems with the pinched wiring until your post.

John