Technically Speaking
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TECHNICALLY SPEAKING – Q & A
Failure to Ignite
sail switch used in models of forced air furnaces
This is the type of sail switch used in all models of forced air furnaces, although the actual switches can differ. If the blower motor slows down below the recommended RPM, the sail switch will shut down the flow of LP-gas, preventing overheating. Although this switch does not fail that often, it does happen.
Bill, I have an Atwood furnace in my cabover camper and I’ve noticed lately that it will only run about 15 to 24 seconds before shutting down completely — of course, no fan and no heat. When I start the engine, the lights come on very bright but the furnace still does not ignite, so I’m pretty sure it’s not low voltage. I know that I have plenty of propane, since I filled the cylinder and have only used the propane to cook a few things on the stove. All of my friends are saying it’s the circuit board, but the circuit boards are expensive and since I’m not sure that’s the real problem, I don’t want to throw a lot of parts at it for no reason. Any suggestions?
—Joe Stevenson

Joe, good thinking about the throwing parts at problems; there’s no reason to start hanging parts on it before you have a concrete diagnosis. There are only three places to look and test based on your description of the problem: the limit switch, sail switch and/or the circuit board. Typically, the circuit boards are durable, so my best guess is to focus on the sail switch. For some reason, the circuit boards fail more often on these furnaces. Also, the limit switches very rarely burn out — but they can.

At this point the only way to really know for sure is to remove the furnace and connect power to it; you don’t necessarily need propane to test it. Without ignition (remember there is no propane to ignite for this test), the circuit board will try three times before it goes into lockout. The fan will run for about 15 seconds, so have your test light ready to go. To test the sail switch with the test light, ground the wire/clip and touch the flat terminals on both sides of the sail switch. If only one side lights up, you have your answer. If both sides light up, test both terminals on the limit switch; if both of those light up then you’ll need to make sure there’s voltage at the circuit board. If you see power, then the PC board is defective.

Two different sail switches are used on Atwood furnaces. If you discover that the sail switch needs to be replaced, you’ll have to remove the one in your particular furnace to match the paddle. There are two different part numbers for the sail switches and it’s critical that you make an exact comparison to avoid installing the wrong part, which will prevent the furnace from functioning properly.

Going Latchless
Seasucker Medium Duty Handle
After trying a less-expensive model (which proved too difficult for me to release) I settled on the Seasucker Medium Duty Handle to ensure the doors to my refrigerator remain closed.
I have a brand new 2023 Grand Design reflection with a large two-door 12-volt DC refrigerator. The problem that I’m having — and from what I can see on the forums, it’s not unusual — is that there is no latch built into the refrigerator, just a strap across the freezer door to the refrigerator door, which doesn’t seem like it would hold the door shut over rough terrain. I can’t believe there was no secure latch provided for this refrigerator and I can’t find anything online. Have you run across this problem before and are there any latches out there that I may be able to retrofit?
—Gavin Schwartz

Gavin, it just so happens that I have the same refrigerator. I’ve done extensive research on the matter and can offer you a couple of suggestions.

After fooling around with straps — which didn’t work — I settled on suction-cup, grab handles that are typically installed in the shower to lend a helping hand for those with physical limitations. All I did was position two handles across the two refrigerator doors, one near the top and one near the bottom.

Suction-cup handles are all over the Internet and Amazon, so you won’t have any trouble finding one. Most of these suction-cup handles will stick well to smooth surfaces, like the refrigerator doors, but you can add a thin coat of vegetable oil to improve adhesion — something people do when mounting monitors on the windshield.

The suction cups held nicely, even on rough roads, but as I soon discovered, it took some doing to get them off (probably because I don’t have long fingernails to get under the suction cups and release the adhesion). While the extra effort was worth not having the doors fly open and scatter foodstuffs all over the floor, I was still in search for one that could be released easier. I recently found a heavy-duty version made by SeaSucker (seasucker.com).

SeaSucker markets a comprehensive line of brackets, racks and camping accessories targeted at the marine and RV industry. I bought the Medium Duty Handle (grab bar) that has two 4.5-inch diameter suction cups. What separates these suction cup devices from others is the way it uses vacuum to provide amazing suction. Pushing a button on each suction cup creates vacuum for the holding power. The suction cups will hold vacuum for 24 hours before additional pumping is required — which is plenty of time for most of us. These suction-cup products are not cheap ($99 for the Medium Duty Handle) but they do work. Considering SeaSucker offers bicycle racks that are only mounted to the vehicle with suction cups, holding refrigerator doors closed is child’s play.

Refrigerator is Too Warm
Norcold Polar 7 refrigerator
Opening the back vent door of this Norcold Polar 7 refrigerator shows some dirt and dust, but overall it’s pretty clean. The chimney tube is on the right, attached to the burner on the lower right.
Bill, I have a 2014 Winnebago motorhome and during our last trip, we noticed that the Dometic refrigerator worked fine while operating on electric — but it would not get cold on propane. I’m assuming that means the cooling unit is okay. We do spend some time off the grid and, of course, while we’re in the boonies and driving it’s on propane. After we’ve driven for four or five hours, the temperature inside the refrigerator hovers at around 55 degrees and the freezer is good. I am unable to get into the local dealer because they’re booked for months, and we have another trip planned. Any suggestions as to something simple I could check?
—Elaine Simpson

Elaine, I’m not sure that this is something you could tackle. Dealing with cooling units, LP-gas and electricity can be too complicated and dangerous for most owners. I highly suggest that you find a qualified RV technician with a lot of refrigerator service experience.

There are only a few reasons that the refrigerator will not cool correctly on propane, one of which is the wrong gas pressure, which must be set at 11 ½ inches of water column at the pressure tap on the gas valve. The pressure at this value can be measured using a manometer — a pressure test should only be done by a qualified technician.

The other common problem is a dirty orifice. It doesn’t take a lot of obstruction to reduce the BTU output of the burner, which in turn will affect the function of the cooling unit. This type of cooling unit requires a certain amount of heat to function — kind of like how an old percolator coffee pot requires a high flame to perk.

Another issue could be that the burner tube is full of rust that blocks the slots where the flame comes out. There could also be rust in the flue that drops to the burner, but this is less common with newer refrigerators. We know it’s not a bad cooling unit as it works fine on electric.

Where’s the Water?
Shurflo Revolution water pump
Shurflo Revolution water pump
The water pump in my 2015 Lance trailer will not come on. The light on the switch in the panel illuminates when the pump has power, which I’m assuming means that the fuse is good. The water pump has always been loud, especially in the middle of the night when someone uses the bathroom. If the pump is defective, I think I would like to upgrade to a quieter model that’s more efficient. Any suggestions on why the pump won’t run and suggestions on a water pump upgrade?
—Walker Stevens

Walker, just because the light comes on doesn’t mean that the water pump has voltage. First, check the fuses; some of them are marked, some are not. If the fuse is good, it’s possible the water pump lost the ground. Use a multimeter to check for power to the water pump and confirm there’s a good ground connection. If there’s voltage at the water pump, it probably needs to be replaced.

If you would like to upgrade, even if the existing demand pump is still good, I recommend the Shurflo Revolution. It’s a good medium-priced water pump, has plenty of pressure (55 psi) and it’s very quiet if installed properly. One thing you need to consider is that the system may not be able to handle pumps with a higher-pressure rating, which can cause short cycling — and it would likely be noisier.

Be sure to replace the inline filter between the freshwater tank and the pump; normally they’re attached right at the pump. Even if you don’t replace the pump, it’s best to check the inline filter before heading out; it’s critical to keep any debris out of the valve system inside the pump.

Are you stymied by a technical problem with your RV? Write to RV Enthusiast Technical Director Bill Gehr at bgehr@rvemediagroup.com. Bill will answer inquiries as space permits.