Problem found.. 2010 LM - 12V fuse for AC keeps blowing

[PJS010LGC]

The 12v fuse for the AC in my 2010 Landmark recently blew while RV'ing. A replacement fuse fixed the problem. Yesterday while parked at home, the fuse blew again but replacement fuses blew upon insertion. I opened up the AC unit ,disconnected the 12V wring and hooked the VOM to the disconnected wiring from the trailer. VOM indicated very low resistance. I pulled the fuse panel, pulled the plus lead for the blowing fuse and checked the circuit at that end. Very low resistance again. But I noticed 2 hot wires coming off this connector, both orange and white. Where does the second wire go because one of these is the orange and white wire that connects to the AC control box. I cant find a wiring diagram for the 12V system anywhere.

Coincidentally, I had the "no 12V power to refrigerator or water pump with shore power disconnected". I discovered the source of this problem yesterday while searching this site, and indeed the breaker had tripped and I pushed the little button back in.

i'd appreciate any assistance in solving this issue.

Regards, John

 

[danemayer]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

John,

I think all the wiring in a 2010 would go through the control box above the air return. If you can identify a connector for 12V DC, I'd unplug it and see if the fuse stops blowing. Careful what you're touching if standing on a ladder.

 

[PJS010LGC]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

Dan,

Do you mean, the air return of the AC unit. I have the connector, on the side of the control box, disconnected, the white with orange stripe wire disconnected from the 12v+ lead into the control box. The tiny wires to the thermostat are still connected, the white with yellow stripe wire and its ground remain connected to the 2 blue white wires going into the control box. I just measured resistance of the disconnected white/orange wires at the fuse panel to the ground buss bar and effectively have a dead short. I fear that I may have one of the 2 white/orange wires touching ground through a spot where the insulation has been worn through. I wish I knew what the other white/orange went to from the fuse panel.

Regards, John

 

[danemayer]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

John,

If I'm following, at the fuse panel, there are 2 orange/white wires that normally are connected to the blown fuse. You have them disconnected from the fuse panel. At the other end, in the control box up in the air return, you have the orange/white wire disconnected. So the only orange/white wire that's not disconnected is the one that goes to some unknown device. And the orange/white wire(s) at the fuse box end have continuity to ground.

I agree that you probably have some location on this wire where the insulation is damaged and there's a short.

Time to check everything else in the coach to see what else is not getting 12V power any longer. That's where the mystery wire goes.

The initial intermittent blown fuse suggests a moving part - perhaps lighting or refrigerator located in a slideout. Don't overlook the bedroom.

 

[PJS010LGC]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

Thanks Dan,

Yes, you read that right. I was hoping that there might be a wiring diagram around that might show the device connected to the second white/orange. I looked but can't find. So you're right, it will be process of elimination. I was thinking that I should separate the 2 white/oranges at the fuse panel and check which one is shorted. If its the other one, then I can at least get the A/C going and the world will not have come to an end ( according to Sharron )

Regards, John

 

[danemayer]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

I agree, separating the wires would narrow it down.

 

[PJS010LGC]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

Dan,

I separated the 2 wires. I checked both leads for a dead short and only one lead was shorted, the other was open. I reconnected the wire that I left the spade terminal on, installed my last 15 amp fuse, checked the 12V leads at the AC control box and had 12 v, reconnected the 12v wires and the harness plug and turned the AC back on. It worked. So I have averted the end of the world, but now I need to find out where the shorted wire goes. It has to go to something that is not separately listed on the fuse panel.

Regards, John

 

[danemayer]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

Start checking interior and exterior lighting, basement lighting, TV signal booster, propane alarm, radio and anything else that has a switch or test button. Something will not be working.

 

[PJS010LGC]

Re: 2010 Landmark - 12V fuse for AC keeps blowing

Dan,
I just remembered that, coincidentally with the first fuse failure, Sharron also reported that the under counter lighting, which is rope LED lighting had quit working. So I went back out to the RV to see if the switch was still on and it was. When I turned the switch off. the wire at the fuse panel when open circuit. Now I know where that wire goes. I then disconnected the actual length of rope lighting from the wire that came from the switch and found that the rope had a dead short. Nothing obvious at the connection point so the rope lighting was removed and trashed. Now I need to find an alternative but we can certainly carry on without the rope lighting so---- PROBLEM SOLVED.

Thanks for your help, Dan, in thinking this through.

Regards, John.