How to Stop Animals From Nesting in Your RV Generator Air Intake

The Quick Answer

Your Onan generator genset intake is being used as a litter box by local cats or other small animals because it provides a perfect enclosed, quiet space that feels safe for them to do their business. Since you've cleaned it three times and you're 500 miles from where you bought the RV, this is definitely a recurring problem with local wildlife finding your generator compartment. The good news is this won't damage your generator mechanically, but it can clog air intake screens and create hygiene issues. You need to install physical barriers to prevent animals from accessing the intake area while still allowing proper airflow for your generator.

What's Causing This

Your Onan generator's intake area is creating the perfect "bathroom" for cats and small animals for several reasons. The generator compartment is typically dark, enclosed, and feels secure - exactly what cats look for when choosing a spot to relieve themselves. Even though you haven't run the generator recently, the residual warmth from previous use or just the protected nature of the space makes it attractive.

The fact that this keeps happening 500 miles from your original location confirms it's not the same animal following you - it's just that generator compartments are universally appealing to cats. The intake louvers and screens provide just enough of an opening for animals to squeeze through, and once one animal uses it, the scent can actually attract others to the same spot.

Class A motorhomes park the generator intake relatively low to the ground, making it easily accessible to ground-dwelling animals. Unlike engine compartments that get hot and have moving parts, generator compartments when not running are quiet, still spaces that animals perceive as safe territory.

Tools You'll Need

• Hardware cloth or fine mesh screening (1/4 inch openings maximum)
• Zip ties or small hose clamps
• Wire cutters or tin snips
• Rubber gloves and disinfectant for cleanup
• Shop vacuum for removing debris
• Measuring tape
• Drill with small bits (if mounting brackets needed)
• Animal deterrent spray (optional)

Step-by-Step Fix

Start by thoroughly cleaning the intake area one more time, wearing rubber gloves and using a shop vacuum to remove all debris. Disinfect the entire area with a pet-safe cleaner to eliminate odors that might attract more animals. Remove the existing intake screen or louver cover to access the opening properly.

Measure the intake opening dimensions and cut hardware cloth or fine mesh screening to fit over the entire opening. The mesh should have openings no larger than 1/4 inch to prevent cats and small animals from entering, but check your generator's manual for minimum free air area requirements as some models may need larger openings or more total screen area to maintain proper airflow. Make sure to cut the mesh about 2 inches larger than the opening on all sides for proper attachment.

Install the mesh screen securely using zip ties or small hose clamps, attaching it to the existing intake louvers or mounting points (note that different Onan models have different intake configurations). The screen should be taut and completely cover any gap that an animal could squeeze through. If your intake has multiple openings or complex geometry, you may need to create a custom screen assembly that covers the entire area.

Test your generator after installation to ensure the screen isn't restricting airflow. Your generator should start and run normally - if you notice overheating or reduced performance, you may need to use a larger mesh size or increase the screen area. Finally, consider applying animal deterrent spray around the generator compartment exterior as an additional preventive measure.

When to Call a Pro

Call a qualified RV service technician if you discover that animal waste has gotten inside the actual generator housing or if you notice any signs of chewed wires, damaged components, or nesting materials inside the compartment. If your generator won't start or runs poorly after cleaning, there may be internal contamination that requires professional service.

You should also seek professional help if the intake design is so complex that you can't create an effective barrier without potentially restricting airflow. Some Class A installations have intricate ducting that requires custom screening solutions. Additionally, if you're not comfortable working around the generator or accessing the intake area safely, a mobile RV tech can install proper animal barriers while ensuring your generator continues to operate at peak efficiency.

Tools & Supplies You'll Need

Fix It Right. Fix It Once.

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