Norcold 3163 3-way refrigerator won’t start on propane, what fixed mine & general diagnostic advice

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If you have not experienced it yourself, I’m sure you have noticed the many threads talking about the problem of not being able to get the 3-way refrigerator started on propane. The burner will start – you can hear the spark clicking and the poof of the burner starting – with a little contortion or a helper you can peer back at the burner box and see the blue flame through the little circular window, but regardless of the position of the thermostat knob and no matter how slooooooowly the safety valve button is released the green light blinks off and the flame goes out.

We have been struggling with this issue for nearly 6 months. A few days before our maiden trip in March with our new-to-us 2016 320S we cooled down the refrigerator on AC, switched it over to propane and let it run overnight – it worked fine. Did the same thing the night before the trip and did the 5 hour trip to the coast (Wright’s Beach, Sonoma Coast, CA) with the refrigerator off. Got there and the refrigerator would not start – could not get the green light to stay on. Repeated level fine tuning was futile. After that trip we had a backyard session trying to get it lit and after several leveling adjustments it stayed on and cooled down. “OK”, we thought, “Leveling is really important – good to know”. It even did repeated successful test starts before our next trip. The night before the trip it’s no go – will not start. At camp it didn’t start no matter how much leveling was done. We did a couple of more trips without a working refrigerator (no shore power at most California state campgrounds).

Over the summer we spent a lot of time on the forum as we set up our solar charging system, moved the spare tire to the tongue, did the PWM fan mod, made up a set of awnings and acquired all the security gadgets. All the while reading every thread regarding this refrigerator problem and trying every technique and incantation that worked for others (slowly opening tank valve, turning on burners for a minute, etc.) Read with trepidation Michigan_Mike’s refrigerator removal to get at the thermocouple. Downloaded the 3163 service manual, the troubleshooting charts seemed daunting.  Read and reread the 2016 thread started by Nomad several times.

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We even called around to local RV dealers and found they either only serviced/repaired units they sold or had weeks long waits to get it in for diagnosis. Finally, after completing the other T@B projects, I had to directly address the refrigerator problem. I focused on putting all the hints, comments and fixes in Nomad’s thread alongside the troubleshooting chart on page 16 of the service manual  and had an —

Epiphany About Easy Diagnosis

There are 4 parts that can cause this problem: relighter ($160), thermocouple ($25-$30), interrupter ($25), safety valve ($40 – $100) – see diagram page 17 in service manual.

I really paid close attention to the last 12 boxes on the “Burner Ignites But Flame Will Not Hold” flowchart on page 16 and had one of those head-slapping Eureka moments — the heart of the diagnosis of this type of problem are the two terminals on the interrupter. All you need to determine which part is bad is a short jumper wire with alligator clips on each end and a multimeter that will measure millivolts at those two terminals. Figure 10 on page 15 of the service manual shows where to test those terminals.

Here is the interrupter and the two white wires attached to the terminals:

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After all these months of dreading the prospect of having to pull the refrigerator out to get at the burner box and thermocouple, I was actually anxious to lift up the burners and do the tests to quickly identify which part was faulty. I had my jumper wire and multimeter ready to go.

I used an Xacto-type knife to cleanly cut through the silicone seal of the stovetop, took the little caps off the screwheads, and used a small star-bit screwdriver to turn the screws 1/4 turn counter-clockwise and lifted up the burners. Instead of rotating it around to sit on the sink I just carefully positioned a 2×4 to hold up the burners. (The propane and electrical wires remain attached to the burners.) In the picture below you can see the clips that secure the burners and why only a 1/4 turn is necessary.

““““““““““““““““““““““““““““

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So, if you are having this problem don’t be intimidated by page 16. If your stovetop burners appear to have a normal flame, skip on down to the box that says “Is the tip of the thermocouple in flame and clean of carbon?”  Since we would have to pull the refrigerator out to find that out – let’s assume it is OK. Proceed to “Is the thermocouple connection at the interrupter tight?” Whoaaa — mine was significantly loose – finger-tightened it about 1/2 turn and snugged it 1/8th or so more with a wrench. PROBLEM SOLVED – green light stayed on first try. After it worked I backed the nut all the way out and used blue Loctite to secure it. This loose nut has been the culprit for others in the forum, but I really didn’t think I was going to be so lucky.

If you are not that lucky then carefully step through the flowchart using figures 9 and 10 to check the wiring connections, connect the interrupter terminals with alligator clips on a wire, if still no flame reconnect white wires and then run the voltage check on each interrupter terminal. Then use the voltages and the last two rows of the page 16 troubleshooting chart to determine which part is bad. For most of us it just takes a few minutes to either fix the problem (loose nuts or wires) or determine which part is faulty. (Full-timers or people with months of continuous use, do face burnt thermocouples and corroded spark electrodes that require pulling out the refrigerator to get at the burner box.)

By making a clean 45° cut in the silicone at the edge of the stovetop it goes back in tightly – don’t think it needs to be cleaned up and resealed (yet).

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Even if you choose to take it to a dealer for repair (say, for a thermocouple replacement where the refrigerator has to be pulled out) it only takes a few minutes to figure out which parts are OK. You will then be equipped to deal with any sort of unscrupulous flimflammery when someone at the shop says, “Well — sometimes a bad thermocouple can cause an electrical cascade and it burns out the interrupter and the relighter, but we’ll let you know.” Hopefully there are other service options. It probably won’t be particularly relevant if you’re at the only service center within a hundred miles, but the “Norcold Limited Warranty Time Allowance Chart” on page 7 is quite informative.

One other interesting tidbit from page 19 – “Diagnosing Cooling Problems” of the service manual states that a marginal off-level infraction allows continued cooling at a reduced level of cooling. The operating limits are 3° front-to-back and 6° side-to-side. Operating outside those limits for an extended period of time can result in irreparable damage. One other very important thing from that page is that if you smell ammonia or see yellow powder around the refrigerator you have a refrigerant leak and the cooling unit must be replaced.

In retrospect it is easy to see how vibration and thermal cycles could loosen a threaded connection that is not supposed to be overtightened and cause the erratic, temperamental and gradually worsening behavior of the refrigerator using propane. 

(BTW: thermocouples are pretty interesting: 

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One final point: Nomad’s 2016 9 page “Fridge Won’t Light for Nothin :-(” thread has all the puzzle pieces on the table. It mentions loose nuts, using volt meters, using the troubleshooting flow charts, which parts worked for several people and much more. Though I read it several times over the last few weeks, I just didn’t see the big picture or understand the nuggets sprinkled throughout the 9 pages. The service manual charts were also a bit intimidating at first.  Along with stories of costly misdiagnosis by techs, the thread does contain a great deal of useful information, photos and part numbers – it was the key for me and I really appreciate the insights scattered around in that thread. I’ve tried to boil it and a few other helpful, relevant threads down to one (rather long) post that gives some direction to anyone who encounters this problem and “pay it forward” for all the tips, ideas and help available in this community. 

Ohh – one other final point: if you are totally new to RVs/trailers like we were, are overwhelmed by all the fun projects and are pushing attention to any Norcold 3-way problem to the bottom of the list, don’t wait any longer. The service manual for the Norcold 3163 (and other models) has detailed troubleshooting flowcharts and wiring diagrams to diagnose common electronic control system problems for all modes using only a volt meter and taking measurements at points that are readily accessible at the top of the refrigerator. 

If you do go poking around in the refrigerator innards please read and follow all the safety precautions – both electricity and gas are lurking – there is risk. If you are a rank novice and don’t understand the value of insulated-handled screwdrivers and pliers, have never experienced the thrill of accidentally letting your screwdriver or pliers tip contact an adjacent wire or terminal or have never appreciated and marveled at how big a spark 12 volts can provide you probably should bite the bullet and seek professional help. ;>)

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