If you've been living the RV life for a while, you probably know the atwood model 8535 iv dclp is basically the heart of your heating system during those chilly nights. It's one of those workhorse furnaces that you'll find in a ton of mid-to-large sized campers and motorhomes. It's reliable, sure, but like anything mechanical that spends its life bouncing down the highway, it can have its moody moments.
When you're out in the middle of nowhere and the temperature starts to dip, the last thing you want is a furnace that refuses to kick on. Let's talk about what makes this specific model tick and how you can keep it running without losing your mind.
What Exactly Is the 8535 IV DCLP?
The name is a bit of a mouthful, but the "8535" part tells you it's a 35,000 BTU beast. That's plenty of power to keep a 30-foot trailer feeling like a cozy living room even when there's frost on the windows. The "IV" just marks the series, and that "DCLP" suffix usually points to it being a door-less, low-profile design meant for specific installations where space is a bit tight.
One of the reasons this model became so popular is the electronic ignition. You don't have to crawl outside with a long lighter trying to keep a pilot light going in the wind. You flip the thermostat, hear a couple of clicks, and boom—heat. At least, that's how it works when everything is going according to plan.
Why Your Furnace Might Be Acting Up
We've all been there. You set the thermostat to 70, you hear the fan start blowing, but the air stays ice cold. It's frustrating, but with the atwood model 8535 iv dclp, there are usually only a handful of culprits.
First off, let's talk about the sail switch. If I had a dollar for every time a sail switch caused a headache, I'd probably be retired on a beach somewhere. The sail switch is a tiny safety device that feels the airflow from the fan. If it doesn't "see" enough air moving, it won't let the furnace ignite. This is a safety feature so your RV doesn't catch fire. Sometimes, it's just dusty, or maybe a bit of dog hair got stuck in there. Give it a clean, and often your furnace will fire right back up.
Then there's the igniter. If you hear the "click-click-click" but no fire, the electrode might be dirty or out of alignment. Or, honestly, you might just be out of propane. Don't laugh—it happens to the best of us. Always check your tanks before you start taking the furnace apart.
The Importance of Good Voltage
Here is something a lot of people overlook: these furnaces are picky about power. The atwood model 8535 iv dclp runs on 12V DC power from your house batteries. If your batteries are low, the fan might spin, but it won't spin fast enough to trip that sail switch we talked about.
If you're dry camping and your lights are looking a little dim, your furnace probably isn't going to light. Keeping your battery bank healthy is just as important as keeping your propane tanks full. If you're plugged into shore power and it's still acting weak, your converter might be the one struggling, not the furnace itself.
Dealing with the Control Board
Inside that metal casing sits a circuit board that acts as the "brain" of the operation. Over time, moisture and vibration can take a toll on these boards. You might see some corrosion or a blown fuse.
A lot of RVers eventually swap out the stock board for a "Dinosaur Board." No, it's not from the prehistoric era—it's just a brand name for a high-quality after-market replacement board. They are famous in the community for being way more durable than the original equipment. If your atwood model 8535 iv dclp is acting erratic—firing up sometimes but not others—the board might be on its way out.
Keeping Things Clean
You'd be surprised how much gunk can get inside a furnace. Spiders, specifically, love the smell of propane. They like to build little nests inside the burner tube, which can block the gas flow and cause all sorts of ignition problems.
Every season, it's a good idea to take a shop vac or some compressed air to the intake and exhaust vents. Just be careful not to poke anything too hard. You just want to clear out the cobwebs and dust bunnies. A clean furnace is a quiet furnace, and it definitely lasts longer.
Noisy Fans and Vibrations
If your furnace sounds like a jet engine taking off inside your cabinet, the blower wheel might be out of balance. These are usually made of plastic or thin metal and can get warped over the years. Even a tiny bit of debris stuck in the "squirrel cage" fan can cause a vibration that rattles the whole RV.
Replacing the motor or the fan wheel isn't the most fun job in the world because you usually have to pull the whole unit out, but it makes a massive difference in your sleep quality. Nobody wants to be woken up at 3:00 AM by a rattling furnace that sounds like a blender full of marbles.
Finding Replacement Parts
Since Atwood was bought by Dometic a few years back, finding parts for an atwood model 8535 iv dclp can sometimes feel like a treasure hunt. The good news is that because there were millions of these made, parts are still everywhere.
When you're searching for a replacement motor or a limit switch, try to have the exact serial number handy. These furnaces went through small design changes over the years, and you don't want to be halfway through a repair only to realize you bought the "IV" part when you needed something slightly different.
A Note on Safety
I can't talk about an RV furnace without mentioning the boring (but vital) safety stuff. If you smell gas, don't keep trying to light it. Turn off the propane at the tank and get out of there.
Also, make sure you have a working Carbon Monoxide detector. These furnaces are "sealed combustion" units, meaning they shouldn't be venting any fumes inside your living space, but gaskets can fail. It's always better to be safe than sorry when you're sleeping in a small enclosed space with a gas appliance.
Final Thoughts on the 8535 IV DCLP
At the end of the day, the atwood model 8535 iv dclp is a solid piece of gear. It's not fancy, and it's certainly not high-tech by today's standards, but it gets the job done. If you treat it right, keep it clean, and give it plenty of battery power, it'll keep you warm through plenty of mountain winters.
Most of the "broken" furnaces I've seen just needed a little bit of attention—a new sail switch here, a cleaned burner there. It's one of those things where a little DIY knowledge can save you a $300 trip to the RV dealership. So next time your furnace decides to take a night off, don't panic. Grab your screwdriver, check the basics, and you'll likely have it blowing hot air again before the coffee is done brewing.