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Refer Operation – Get the best out of your RV refer
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What to do about the refer flame
Around 2 months after I bought the rig, I drove down to Walla Walla to visit a sick friend. On one of my many stops during that trip, I noticed that the refer had switched off and the ‘Check’ light was on. So I started watching it as best I could. Since I’d just paid $525 for a new refer cooling coil assembly, I was concerned there might be a problem with it or with our installation. What prompted the replacement was a strong ammonia smell emanating from the refer and of course, no cooling.
I was lucky that my son’s best friends dad was a recent ‘Mobile RV’ tech (got out of the business and went back to a dealer). Since my son had helped him so often with fixing or upgrading his computer, he did the replacement for me free, I just paid for the replacement part. We did the whole job in his driveway in around 2 hours. It’s not easy, takes specialized knowledge, and having an experienced tech was, well, required.
Anyway, here it was, going into ‘Check’ mode. I tried restarting and discovered that it would start right up and then go to ‘Check’ whenever I got up to around 55 MPH. Hmmm. There was a slight 10-15 MPH cross wind. Don’t know why, but I just figured that since it had just been serviced, that it was likely that the side wind was blowing out the flame and it wasn’t really a refer problem. So, I removed this cover:
and taped a piece of paper inside the cover to block the side wind since I thought that was the problem. Here’s a shot of under the cover. Note that the plate on the right is suppose to keep the flame lit in strong winds but doesn’t seem to do the job. In this shot, the front of the rig is to the right:
I ran with the paper cover for miles, stopping and cutting bigger pieces and taping them into place on the inside of the cover until I had just the right size and the flame didn’t blow out anymore. Then I went on several trips where there wasn’t a side wind or it was from a different direction. I did several tests of the paper baffle I’d made, usually enlarging it, to see if I had the optimal size or if it was needed at all without a side wind. Turned out that without the added baffle, the flame would blow out pretty regularly no matter which direction the wind was coming from or even if there was no wind. Get the rig up to 55 MPH or over and the refer flame would always blow out. Seemed a little funny to me that there weren’t any receipts for repair of this issue in the service documents that came with the rig…and I didn’t find much on RV.net either. In any case, I felt that the problem was a design issue, not an age, adjustment or repair issue, so a little redesign was in order.
The baffle size I came up with experimentally is 9″ X 15″. The long side is positioned along the bottom inside of the cover, then it’s taped in place with packing tape (which needs to be replaced once per year) on the bottom and top, no tape is used along the sides. I cut it so that it doesn’t cover any of the top vent row. I found that a semi-rigid plastic table mat works well and has lasted nearly two years. The positioning doesn’t cover any of the vent holes, it just routes the outside air around the added baffle, which I believe prevents the air flow from interacting with the propane flame too much while providing as much combustion & venting air as is required.
Here’s the picture of how I placed the baffle, note that it’s left side is positioned to the right side of the access hole when it’s installed, this would be toward the front of the RV since my refer is on the passenger side of the rig:
This fix has worked now for 22 months and in that time I have only had two, three, experiences of the flame blowing out. Those occasions were while I was running from a tornado in Nebraska or with really strong side winds. One thing I do is remove the vent cover and place it in the house when the outside air temp is above 85F or so (and I’m parked). I don’t want the refer to be gasping for air when it’s hot out.
Update: Late 2011
It took a while for me to realize it but the reason the flame was blowing out so easily is because the thermocouple was misadjusted. It wasn’t far enough into the flame to keep it at the right temp so the circuit would keep shutting off the refer and switching it to ‘Check’ when the wind flickered the refer flame a little. This ‘make do’ fix, although it worked, was unnecessary and I removed it. See the next posting for the real reason the refer would go into ‘Check’ after driving…
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Refer Problem – Flame won’t stay lit…May 2011
After I moved back into the RV, I set about testing all my appliances and equipment. When I got to the refer, I found that it two problems. First, when running on AC, the check light would come on randomly. A quick check outside and I found that the tech that replaced my control board back in ’09, had connected the system ground wire under a stripped screw. It was loose and wouldn’t make good contact occasionally. Screwing that under a nice tight screw solved that initial problem.
Then when I’d fire it up on gas, it would run for 45 seconds, then shut off the gas and give a ‘Check’ lamp.
I tested for all the normal problems, such as no gas, but the flame was nice and strong while it was running, the kitchen stove flame looked good, no sputtering, the tank gauge showed 1/2 tank, so I was confident that it was getting ample gas.
Flame, Thermocouple & Sparker
So I moved out to the outside refer compartment that houses the flame assembly & control board. I’d just replaced the board back in ’09, and since I usually run the refer on AC, it couldn’t have more then 200 hours on it so I was confident there was some other problem, since these boards last for 10 years easily.
Control Board.
After disconnecting the 120Vac plug and the 12V wire, I knew (because it is the only sensing device that controls the flame – other then the thermistor, a small electrical device that changes resistance as temperature changes, inside the refer that controls temperature) from looking at the schematic glued to a cover plate that the thermocouple is the most likely culprit with my symptoms so I concentrated on that device. I had to remove the plastic cover off of the board shown above to access the thermocouple input. Where that red meter wire is connected. Then the other lead from the thermocouple is connected on the terminal opposite that yellow clip wire. As I was messing around there, I noticed that the white wire connected to that terminal was loose. Not sloppy loose but easily wiggled.
First I measured the DC resistance of the thermocouple – turned out to be over 2 ohms. These devices are basically a dead short, they use special ‘thermocouple’ wire to connect to a circuit and are pretty sensitive to bad connections. All they are are two wires of dissimilar metals. They are crimped together with a special metal collar or they are spot welded. When exposed to heat, the junction of the wires developed a tiny voltage that can be sensed and used to control a circuit. In this case, that voltage is used to tell the refer if the flame is still on, if the voltage is too low, that means the flame has or is going out, or the thermocouple is position mis-adjusted. The control circuit would want to turn off the gas supply in that event.
The resistance was too high. So I gently crimped the loose terminal and measured again. Down to 0.9 ohms (most of that resistance is caused by the meter leads). Much better. Reconnected the 12V and fired it up and instead of shutting off in 45 seconds, it stays lit. The voltage generated by the thermocouple starts at 2.2mV (.oo22V) when the flame first comes on and quickly ramps upward. It hovers around 10mV (o.o10V) after it’s stabilized and that voltage keeps the ‘Check’ light from coming on. You must use a digital volt meter to measure voltages that small.
I did adjust the physical position of the thermocouple so it was a tiny bit further into the flame as it has been known to occasionally flame out while I’m driving, what with the wind whipping around inside the cabinet. But I find that the adjustment isn’t adequate as it doesn’t really hold well, it looks as though it came that way from the factory, so I’m going to leave the wind block I’ve installed to the outside cover (see article above). I can put up with the road wind blowing out the flame occasionally as I’m driving as the refer doesn’t warm up that rapidly. I’m in the habit of checking the status light whenever I stop.
Gas shutoff.
Another test was to shut off the gas using the handy shutoff valve shown above. It immediately started to spark, and if I’d left it off, it would have shut down the gas and activated the ‘Check’ lamp. Restoring the gas caused it to operate normally.
Finally, I buttoned it all up in the outside compartment and checked it…everything seemed to be fine, except when I opened the refer door. Then all the LEDs in the eyebrow controller above the refer just went out! Like the refer was turned off. Removing the lamp would fix it, but the lamp wasn’t shorted. I remembered that I’d had this problem off and on for years, but it was always intermittent and I’d never been able to track it down. This time it was failing regularly. Every time I pushed the inside light switch with the bulb installed (turning the interior light ‘Off’), the thing would turn ‘On’ the control. Let it go (turning the interior light ‘On’), it would go back off. Weird. No wonder I hadn’t worked on it.
Since I’d been working out there in the refer compartment for hours, I had noticed that there was allot of strain on the two cables that come down from the eyebrow control. I hadn’t liked that at all, but I’d left it alone. The main cable, which has several wires in it has a crunch/kink in it that I didn’t like either. And there was the possibility that I’d done something wrong.
Although I was careful to only remove single wires and then replace them while I was working on things, stuff can happen.
Anyway, I went back to work trying to isolate the issue…without help this is fairly difficult as the refer is inside and the controller is outside. I found another loose connector on the control board itself and fixed it but didn’t really think that was the problem since it wasn’t that bad.
This time the issue was returning every time I reconnected power where as in the past, it would go away rather quickly. So, thinking about it, I decided that it probably had something to do with the strain on the control cable. If you’ll glance back at the Control Board picture, you see two gray cables connecting to the board. Those cables are routed down to the bottom of the plastic case and then route up through a large hole there. I wanted to give it some strain relief so I drilled and cut out a hole in the control board plastic cover to the left of the connectors where the cables plug into the board. Doing that took all the strain off the cables with the shortened routing. Once that was done, the problem seemed to disappeared. What I think is that up above in the refer compartment, the strain on one of those cables was intermittently shorting out a couple connectors. A low resistance short but not a dead short, so the board would turn itself back on after it was removed, such as opening the light circuit. Or, the wicked crunch the control cable exhibited has cause a couple tiny wires to short together under the right strain conditions. I didn’t want to get into stripping back the cable jacket, cutting the wires and repairing them, so I’ll just let it go for now since it seems to be working OK.
The other possibility is the 12V & ground terminal strip. If the higher current of the bulb causes a dirty connection to increase in resistance, that could shut the board down without damage, which was what appeared to be happening, so I removed all the wires from that connector, brushed them down and reinserted them. There are metal crimp caps that the control board ground and the return from the refer light (and switch) are terminated into and after all these years are looking a little corroded. That could be the problem but I really don’t know at this point. I’ll remember this if the problem comes back though.
This board is really super simple. It doesn’t have ANY active components, just a few diodes, caps, and a couple relays. The only thing that might be failure prone are the relays, and those can be found for under $5 each. Next time I have some extra time, I’ll pull the board and work out a schematic so I don’t have to waste another $220 on a new one…but I’ll likely sell the rig before that happens.