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Old 02-11-2016, 11:35 AM   #1
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Looking for gracious SOB help

My knowledge of Sprinter based B vans is limited to common systems to trailers, and this request for help stretches to SOB Sprinter questions (Pleasureway). He lives 300 miles away, so I can't see it from here

Situation: My brother has an 07 Sprinter B van. He has been having trouble with his fridge (Dometic Type C40/110; Model # RM 7401L) cooling well on electric, but not on gas. In addition his generator (Onan Model #2.5KVFA26120L) will only run when covering the air horn with a rag....effectively providing a "choke".

This is what I told him in an email:

"It's difficult to be accurate without seeing and diagnosing in person, but here are my suggestions"

Generator:

It's definitely not getting enough fuel, based on that it will run with a rag applying a "choke" to it. This can be the result of several things: 1) low LP pressure. Inspect all lines running to Onan for kinking or evidence of a rock or whatever collapsing the line. If they are rubber, they can deteriorate internally and peel the inner layer, causing a restriction of gas flow. Also, although rare, there are oils that precipitate out of propane and can settle in a low point in the line and cause a restriction. 2) the regulator at the tank for the whole coach should be tested for regulated pressure. This is usually done at the stove line. ALL other gas appliances should be on and running (furnace, water heater, etc.) and the spec should be 11" gas pressure. This usually results in about 14ish" of static pressure when all appliances are off. There is and adjustment at the regulator for pressure output regulation. 3) I do not know if the ONAN utilizes a "step down" regulator, like the stove, (and I doubt it), but it could be bad, if present.

Fridge:

I am unclear if this fridge has a two stage flame where there is always a pilot flame or not. I don't think so, as they reference an automatic spark igniter. Since you have a flame, I am wondering (assuming the chimney is clear and the flame alignment to the gas absorption tube is accurately applying the full flame heat) if this might be an entire coach system low pressure issue as well.

Quick check. all your gas appliances should have a HARD blue flame with a strong hiss or roar while in operation at the burner while on high. The stove should sound like your home stove, and the flame should be blue with a rapid but minor "dancing at the tip. If the flame is lazy, no hard dancing, and/or has yellow or orange tips, pressure is low.

If the furnace doesn't roar like a jet engine and/or you see soot staining on the vents or side of the coach, this can be an indicator of low pressure.....same with water heater.

I would suggest a pressure check with a gauge at the stove if your flames are suspect first."

What might I be missing?

Other information: 1) fridge chimney has been checked for blockage (although not completely removed)

2) I also told him to check fridge burner alignment with respect to the absorption tube.

Naturally, when he found someone who will look at his ONAN, the pre-estimate was $1000 and an RV dealer wants to REPLACE his fridge..$$$.

Questions that I don't know the answer to:

Does the ONAN have a step down regulator, or run off house regulated pressure?

Does a factory LP ONAN have a carburetor...or a gaseous throttle body?

Any other suggestions? From a distance, I think the two problems are related and there is a propane pressure issue.
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Old 02-11-2016, 02:28 PM   #2
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I can't comment on the generator as I don't have troubleshooting experience with those. The only thing I can add regarding his potential for gas-related problems is to check and make sure he's not losing gas pressure via a leak. That was the case with ours, and you can read about that in this blog post.

Regarding the fridge, replacement actually might be the way to go. I don't know his model number but when I call the manual for the type you cited, I get a PDF that looks similar to the Dometic 2351, which is the model that T1N Interstates were mostly born with. I'm betting it has similar construction components because it's about the same age.

Our original 2007-era 2351 would work on gas but not electric but only erratically - sometimes it wouldn't work at all. We fiddled and futz'd around spending money and time replacing this component and that component. Front electronic control panel - replaced. Large black fuse-containing internal cube-shaped component whose name escapes me - replaced. And the thing still wouldn't work properly, so we bought a new 2351 which has worked flawlessly. We got it new but surplussed (it was missing its front panel, which we fabbed ourselves) for about $680 after wasting probably $150 replacing parts that didn't fix the problem. Here is a blog post describing the DIY replacement.

So yeah, I get where you're coming from re: frustration with dealer saying "just replace it". That's often the stupid and/or lazy way out. But with older Dometics, it might be the most practical and efficient way out.
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Old 02-11-2016, 03:53 PM   #3
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Thanks, and certainly a leak could be a concern and that will be performed while the gauge is hooked up for the pressure test. However, he has noted no irregular LP consumption nor any odor anywhere.

As far as the fridge, and this is just me and the way I'm built, but with it cooling so well on electric, I am CERTAIN that the expensive parts are good. This makes it just a matter of accurate strategy based diagnostics. Part of that strategy is collecting experiences of others with a similar install and model....so thanks for your input. You could be right if parts are outdated and high priced. Ran into that with a home appliance...."there's only a few left on the planet, bend over please."
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Old 02-11-2016, 08:12 PM   #4
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If the fridge works when the electric heat (120v) is applied, it sounds like he isn't getting a flame.

The fridge uses an electric ignitor instead of a pilot light. Like cars that don't run, it's either bad fuel, air, or spark. Unless there is a plugged vent the air should be fine as you noted. If he has good gas at the stove, the remote propane valve is open at the tank which points to the fridge. So it could be the fridge's 12v power, the propane valve, the orifice in the propane jet, the ignitor, or the electronics board that controls the ignitor. There is a fuse on the circuit board in the back of the fridge which is a bit difficult to find. I'm not sure if it protects the 120v or 12v systems.

It could be a simple $3 repair or a frustrating 3 day troubleshooting effort.
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Old 02-11-2016, 08:17 PM   #5
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He has a flame, he just can't tell me from my description of what it looks like whether it is a normal hard blue flame. The only reason I asked about the ignitor vs pilot is my old sob and my popup before that had a two stage flame. I wondered if they still made those and if his was never going to high flame.
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Old 02-11-2016, 08:57 PM   #6
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I just reviewed my Dometic manuel and it looks like they are all one stage burners. They don't troubleshot "have flame won't cool" but they stress the importance of a nice blue flame.
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Old 02-12-2016, 05:35 AM   #7
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FWIW on the fridge, someone just hatched this thread on a very similar problem:

http://www.airforums.com/forums/f425...ic-146662.html
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Old 02-12-2016, 07:21 AM   #8
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It's nearly impossible for those things to not cool when heat is applied. The vent stack has a sheet metal door at the bottom (may be covered by insulation). If he opens that door he can see the ignitor, and the flame.
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Old 02-12-2016, 07:28 AM   #9
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Originally Posted by LB_3 View Post
It's nearly impossible for those things to not cool when heat is applied. The vent stack has a sheet metal door at the bottom (may be covered by insulation). If he opens that door he can see the ignitor, and the flame.
You are very right, my problem is...the van is 300 miles away and my brother is very non-technical. If the flame is not aligned with the bottom of the Absorption tube, there can be cooling problems on gas.
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Old 02-12-2016, 07:30 AM   #10
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So, I was talking to him yesterday, and advised it might be worth the $50 to just go ahead and replace the regulator and test my theory...it's 9 years old anyway, but neither he nor I know where it is. I sent him a pic but he didn't locate it. I'm sure pleasureway is different that AS, but where dot the manufacturers typically install the regulators in relationship to the high pressure lines exiting the tank?
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Old 02-12-2016, 07:48 AM   #11
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Quote:
Originally Posted by dznf0g View Post
I'm sure pleasureway is different that AS, but where dot the manufacturers typically install the regulators in relationship to the high pressure lines exiting the tank?
Right at the tank would be my guess, but in any event somewhere between the tank and the first branch in the supply line.

The propane system in just about any B-van, regardless of manufacturer, is bound to be similar. They're all off-the-shelf ASME tanks installed in accordance with NFPA 1192.
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Old 02-12-2016, 09:31 AM   #12
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Right at the tank would be my guess, but in any event somewhere between the tank and the first branch in the supply line.

The propane system in just about any B-van, regardless of manufacturer, is bound to be similar. They're all off-the-shelf ASME tanks installed in accordance with NFPA 1192.
Thanks, and do they look just like the trailer ones? (except no switchover valve)
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Old 02-12-2016, 11:40 AM   #13
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Old 02-13-2016, 07:28 AM   #14
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LB_3 (my husband) posted three pics from our tank replacement. If the owner can get any tank work of any kind done for $50, I'd say go for it. The issue we had with our tank is that there is no room to work on it under the Class B. We were told that anything that had to be done required removal of the tank so that it would be accessible. Labor charges would have been very high relative to the cost of a new tank which is why we decided on replacement (the original was badly corroded anyway).
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