Understanding Airflow & Freeze-Ups in RV AC Systems

This episode of The Todd & Tony Show is brought to you by Big Beard Battery

If you’ve ever wondered why one part of your RV is nice and cool while the other feels like a sauna—or why your AC suddenly starts freezing up for no clear reason—this episode of The Todd & Tony Show dives deep into the mechanics of RV airflow problems and how to diagnose them.

Whether you're full-timing in your rig or just gearing up for a summer trip, understanding how your air conditioner works can save you time, money, and frustration.

RV Airflow Problems: The Whisper Quiet Dilemma

Many RVs today come equipped with Whisper Quiet air conditioning systems. While they’re great at reducing noise, they can also make it more difficult to troubleshoot airflow issues because the lower control unit (where the filter, plenum, and airflow adjustments usually are) is hidden behind the ceiling instead of being accessible from inside the RV.

In this episode, Todd explains that:

• If one zone (like the living room) has low airflow while another works fine, the issue is likely with the plenum—the air distribution chamber between the AC unit and the ductwork.

• Over time, divider plates can shift or become loose, allowing cold air to leak into the attic space or dead zones.

• Fixing this may require removing the rooftop shroud and carefully lifting the AC unit to inspect underneath.

If that sounds above your DIY comfort level, hiring a qualified RV technician is the safest path forward.

Freeze-Ups & Fan Failures: What’s Really Going On?

Another listener question involved a common but confusing issue:

“My RV AC won’t kick on in low fan mode, and it freezes up when on high. The coils are clean. Could it be a capacitor?”

Todd and Tony break it down step by step:

• First, determine if the fan is spinning at all. A fan that doesn’t move in low mode but runs in high could point to a capacitor issue or bearing failure.

• Airflow is everything. Without proper airflow across the coils, the refrigerant boils too cold (around -40°F under pressure), and the coils will freeze over, even if they’re clean.

• While some might suspect low refrigerant, RV AC units are sealed systems. If it’s leaking, it’s typically empty—not just “low.”

• Diagnosing this properly requires testing the capacitor and motor function. If you're unsure, it’s best to let a professional handle it.