Refrigerator 12v ignition sense wiring

Electrical issues, both 12 volt and 120 volt
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Mgittrich
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Refrigerator 12v ignition sense wiring

Post by Mgittrich »

To operate the fridge in the 12v mode airstream has placed a relay in the circuit requiring the engine to be running. The reason for this I assume is because of the relatively high amp draw (10-11 amps/hr) and the small house battery capacity (55 amp/hrs).

For quite awhile I've been concerned that the fridge was not running in 12v mode but was unable to confirm this. After removing the couch in preparation for upgrading the converter and adding batteries under the seat I decided to review the existing wiring for the power seat and fridge, see my other post on this topic. So I took out my dc ammeter to verify the fridge amp draw and discovered that there was no ignition power going to the relay and thus no power going to the fridge with the engine running.

So my question is does anyone have any idea where airstream is getting the ignition power to flip this relay?

The ignition sense is a yellow wire attached to the relay and routed to ??? Via a wire loom exiting out from the couch box. My assumption is there is a blown fuse or disconnected wire. Before I spend a lot of time trying to track this down or just removing the relay I thought I'd see if anyone else has run into this problem.

Thanks for any insight on this.

Mike
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Planck
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Re: Refrigerator 12v ignition sense wiring

Post by Planck »

Mike

I have all of the factory E350 manuals. While a little rusty a reading them(need to know their system), I find yellow wires labeled "modified vehicle power" going to location B on the engine compartment fuse box. It is either 50 or 60 amp, depending on which part of the manual you use. Also, under the dash on the drivers side is a 30 amp in location 16 that is called "modified vehicle power". Not sure what color wire, as they show a yellow part way and a black/white part way. Might be worth a try looking at those two fuses.

Phil
Mgittrich
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Re: Refrigerator 12v ignition sense wiring

Post by Mgittrich »

Planck, thanks for the info I'll check it out.
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Re: Refrigerator 12v ignition sense wiring

Post by twistedskipper »

Mike,

I'm having the same problem (no 12-volt refrigerator operation with engine running). This seems like a nearly essential capability, otherwise I have to run the fridge on propane while driving.

Did you ever track down the wiring paths for the refrigerator 12v circuit?

Also, where is the ignition sense relay physically located on your 190?

Thanks!
--
Tim
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Re: Refrigerator 12v ignition sense wiring

Post by EverAfterRanchMotors »

We recently acquired a 93 B190 and the fridge has me perplexed. The wiring is the same (two breakers and a relay behind the converter), but I'm not getting 12V power to the fridge... ever. I have no books to see if I'm missing a switch somewhere, so I'm hoping there's one hiding and this will be easy. I'd sure appreciate any insight on how to get power from one side of this relay to the other... or if this has anything to do with the 12V fridge power source at all.

I guess the main question is: how does the green wire feeding the 12V connection at the fridge get its power?
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Planck
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Re: Refrigerator 12v ignition sense wiring

Post by Planck »

With the engine running, there is no 12 volts at the relay on any terminal? If so, you will have to work back to the van wiring. Possible a fuse has blown, if it is a fused circuit. I have the factory Ford manuals for 93. Will try to see if any clues there.
Mgittrich
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Re: Refrigerator 12v ignition sense wiring

Post by Mgittrich »

I never did track the issue with the ignition sense wire on the relay down before I put my RV into storage for the winter. When I started looking at the issue again after checking all the connections and unplugging and plugging in all the relay connections in the spring, the relay began working correctly. So I'm not sure if I had a loose connection or wasn't propperly measuring the relay output or whether the relay was connected properly.

After I figured this out, I checked to make sure that I was getting voltage to the fridge 12v element and I was. The fridge still would not keep food cold in 12v operation mode. So when I took the RV to the shop I had them check the element and it was bad. So I had them replace it. This was not a cheap repair. The cost of the element was $165 plus installation which brought the bill to about $250.

So after all this, the fridge worked properly in 12v mode.

In retrospect I wish I had not repaired the 12v mode as the fridge does a poor job of keeping frozen and refrigerated fool cool even when the outside temperature was in the 60s on the Oregon coast. So I ended up just running the fridge on gas while traveling. The fridge worked very well and I did not experience any blowouts while driving over the 3000 miles I put on the RV driving from Oregon to Kansas City.

I know this is a little risky but it works well.

Good luck with your research and repair. Let me know if I can be of further assistance.

Mike
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Re: Refrigerator 12v ignition sense wiring

Post by EverAfterRanchMotors »

Well, we've had enough. We're just going to sell it as it sits without the fridge running. It may very well be something stupid which keeps it from operating, but I'm, as they say, at my wit's end. I wired the 12V supply directly to the fuse panel, so both the 12V and 120AC are hot. Still no worky. We've got a TON of money into this unit and I'm afraid it's already going to be a loss. 28,000 miles on this van-- new tires, upholstery, carpet, a/c, and THOU$AND$ spent on engine, tranny, and the rest of the drive train just to get it running and looking great. It's really too bad about the refrigerator though, since it's literally never been used-- still has tape and cardboard inside.

I guess I'll try running the fridge on gas tomorrow and see if that system works.
Mgittrich
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Re: Refrigerator 12v ignition sense wiring

Post by Mgittrich »

Sorry to hear your still having problems.

One of the things I noted with my Dometic is there are no lights to indicate that it is running. On my unit the control knob positioning is critical to get it to run. It has to be positioned just right or it won't operate. You might try playing around with this.

Good luck.

Mike
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Millennial Falcon
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Re: Refrigerator 12v ignition sense wiring

Post by Millennial Falcon »

So, if I want the fridge to ALWAYS have 12-volt power... what do I do?

I've found this elusive relay with two inline chunks (circuit breakers?) behind the fuse panel under the couch in my 1994 B190.

Is it best to just cut the relay out of the circuit entirely? Maybe just cut the green and black wires and splice them together?

Has anyone else removed this relay?

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Re: Refrigerator 12v ignition sense wiring

Post by skater »

I would remove the relay and run the white wire (probably need to splice a new wire in) to the RV fuse panel. But mine has extra fuse slots available; yours might not. If it doesn't, I'd look for a circuit with only a few things on it.
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Misplaced Vermonter
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Re: Refrigerator 12v ignition sense wiring

Post by Misplaced Vermonter »

128DB0E9-AC83-4717-8311-180908968B6C.jpeg
128DB0E9-AC83-4717-8311-180908968B6C.jpeg (31.08 KiB) Viewed 7709 times
[/img]Millennium Falcon... what did you end up doing? Do you have more pics of your relay and how you spliced it? I’ve run into the same situation.. needing constant dc to new fridge.. aside..are you on the b190 FB group?
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Millennial Falcon
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Re: Refrigerator 12v ignition sense wiring

Post by Millennial Falcon »

Misplaced Vermonter wrote:
Sun Aug 23, 2020 1:40 pm
128DB0E9-AC83-4717-8311-180908968B6C.jpeg[/img]Millennium Falcon... what did you end up doing? Do you have more pics of your relay and how you spliced it? I’ve run into the same situation.. needing constant dc to new fridge.. aside..are you on the b190 FB group?
I solved the problem as discussed in this thread.

Basically... I snipped the green wire and capped the end that comes off the relay for it. I just left the relay there since it's not hurting anything.

Then I fed the green wire through into my couch fuse panel and screwed it into one of the unused terminals. I put a 15amp fuse in there, and now the green wire will ALWAYS be hot when the coach 12 volt system is online. This is why I wired in a switch between the green-wire and the fridge in the fridge compartment, in case I want to totally isolate it and turn the unit off.

I know some people have just cut the green and black wires and pigtailed them together. This would give the same effect, but I wanted to put a fuse in the system, and figured it was cleaner to just use the fuse panel, especially since it was right there and didn't even require me splicing in any extra wire to reach it.

It's been running just fine for over a year now!!
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