Welcome to the first entry in November’s Medium Mod Contest. One Medium Mod will be published in every Email Alert in November. At the end of the month, we’ll hold a reader vote to determine November’s winner. Click here for information about the 2023 Mod Contest, including how to enter.
Steven Osburn, Poulsbo, Washington
Lawnmower Throttle Meets Stove Vent
2019 Ford F-350
2023 Northern Lite 10-2EX
This modification is a variant of what others have submitted here in TCM.
One thing I’ve always found annoying about RVs is the stove vent cover; that little flap cover on the outside of your camper with turnbuckles to keep it from flapping in the wind.
If you close the cover, you can’t use your exhaust fan. If you keep the cover open, you get a “flap, flap, flap…” sound all night when it’s breezy. To make matters worse, to open or close the flapper on a truck camper, you have to be 8 feet tall (with 3-foot-long arms).
I’ve seen people bring ladders for this job, but I don’t want to carry a ladder. I’ve seen people use poles to poke and pull the turnbuckle, but that’s a pain, especially if you forgot to open the flapper before you started cooking bacon, and are trying to not let the smoke alarm go off, which would spook the cats, which could cause you bodily harm (but I digress).
I’ve even seen a pretty ingenious solution where one Truck Camper Magazine reader used a linear actuator to open and close the flapper based on the fan power switch. I wanted a mechanical solution. Wouldn’t it be nice to be able to just manually open and close the cover from inside the camper?
While rummaging around in my shop (which is how I typically get inspired), I ran across a new, never-installed generic throttle cable for a lawn mower I no longer own. Of course, like all mechanically inclined people, I keep stuff in my shop “just in case” and finally, it paid off! All I had to do was figure out how to use the cable to open/close the flapper when needed, without making my fan hood look too much like a lawnmower control system.
After removing the fan hood assembly from under the cabinet, I found that the fan was screwed into a metal housing permanently mounted into the hood with rivets. I needed to separate the fan housing from the vent hood to gain access to the back side of the flapper. That was pretty easy. I drilled out the rivets, pulled out the fan housing, and then added a few brackets and screws so that the fan housing could be removed/installed without having to remove the hood. This gave me access to the back side of the flapper while the stove hood was still in place.
The throttle cable was much too long for the distance between the flapper and the hood, so I cut the throttle cable and cable sleeve to the length needed.
Note: you should cut the cable sleeve first, then cut the cable, then put a bend at the end of the cable so that it has a hard stop and won’t pull out of the sleeve any further than you want it to.
Then, I drilled a hole for the throttle cable in the front of the fan hood and routed the cable to near the flapper location. That required drilling a second hole in the vent hood.
In normal operation, the air pressure from the fan is what opens the flapper, and I didn’t want to change that. I wanted the cable to pull the flapper closed, but not push it open. To achieve that, rather than a hard connection between the cable and the flapper, I added a small piece of cord and a cord lock. Now the cable can pull the flapper closed, but the cord won’t push the flapper open. The purpose of the cord lock is so that I can adjust the cord length without having to tie knots. In theory, I shouldn’t need to adjust it now that it’s set to the right length, but I like the option.
That’s all that is required for this mod. Pulling the “throttle” out closes the flapper vent. Pushing it in allows the vent to operate like normal because the cord is slack. However, since Murphy visits when it’s least convenient, what if you turn on the fan but forget to open the flapper?
I’m sure we’re not the only ones to have done that. It goes back to the smoke alarm and the cats causing boldly harm. I wanted something to remind me, so in addition to the throttle control cable, I went a step further and added a reed microswitch and magnet, coupled with an LED tied to the fan power switch so that a blinking light turns on if the flapper isn’t open but the fan is running. That part isn’t really necessary, but it was cool, and I already had all the parts on hand.
This mod has worked great. We now keep the flapper closed unless we are using the vent, so no more “flap, flap, flap” in the wind, but we can quickly open it when needed. It’s also pretty foolproof. Very little can go wrong because it’s just a cable and an LED light.
The materials were:
– Lawnmower throttle cable (no idea what this costs now, but I’m sure they are cheap)
– Cord lock (had this on hand as well)
– Reed switch (part of an alarm system window monitor, but they can be found on Amazon or eBay).
– 12V blinking LED (also Amazon; had these on hand from a previous project or two)
If I had to buy everything from scratch, I doubt the cost would be more than about $30, and you’d end up with lots of extra LEDs and reed switches at that price.
It took me two hours to complete this modification. In my opinion, the skill level of this modification is medium because it requires drilling and making some brackets.
Disclaimer: The modifications above are submitted by Truck Camper Magazine readers. It is your responsibility to make sure that any do-it-yourself modification project you undertake is safe, effective, and legal for your situation.
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