Two-Minute Tech Tip Tuesday | Brought to you by NRVTA – the largest hands-on RV training academy in the U.S.
Welcome back to another Two-Minute Tech Tip Tuesday! Whether you're troubleshooting a problem or just brushing up on RV know-how, we’ve got a cool one for you this week—literally. Don’t forget to hit that subscribe button so you never miss a tip that could save your trip (or your sanity).
🧊 This Week’s Question:
“Why can’t my air conditioner run on low without freezing up and shutting off? It works fine on high, but on low or automatic, it freezes.”
– JackM1dB (yeah, we’re pretty sure you’re a sound guy with that username 😉)
Jack’s running a Dutchmen Kodiak with a Dometic 35,000 BTU A/C, and he’s dealing with a common issue—freezing coils when using low or auto settings. Let’s dig into why that happens and what you can do about it.
💨 How Your RV A/C Actually Works
Your air conditioner cools your RV by pulling warm, moist air from inside and blowing it across cold evaporator coils. As the warm air hits those coils, the moisture in the air condenses—just like a cold soda can on a summer day.
Now, here’s the kicker:
When you’re using the low fan speed, there’s less airflow. That means the condensed water just kind of hangs out on the coils instead of being pushed off.
And what happens to water sitting on a freezing surface?
👉 It turns to ice.
🧊 What Happens When Your Coils Freeze?
When the coils freeze over, the system can’t do its job. That’s where Dometic’s built-in safety feature comes in.
Inside the A/C unit is a thermistor—a small sensor that measures temperature via electrical resistance. When it senses things are getting too cold (aka freezing), it shuts off the compressor to prevent damage. Meanwhile, the fan keeps running to pull warm air across the coils and melt the frost.
Once everything's back to normal temps, the compressor turns back on.
Totally normal. Totally smart. And totally by design.
⚙️ What About the “AU” (Auto) Setting?
Jack also asked about running his thermostat on Auto.
This setting is designed to start on high speed, then switch to low as the RV cools down and reaches the desired temp. While this saves energy, that low fan speed can trigger the same freeze-up issue—especially in humid conditions or if airflow is restricted.
🔧 The Bottom Line
✅ Freezing up on low speed is common—especially with high humidity.
✅ Your A/C is doing what it’s supposed to by cycling the compressor.
✅ Auto mode is smart and safe—no harm to your system.
If freezing happens too often, try switching to high fan speed for more consistent airflow. It could also be worth checking your vents or filters to boost circulation.
🛠 Final Thought
Whether you’re a weekend warrior or full-time RVer, a little understanding of how your A/C works can go a long way in helping you stay comfortable on the road.
And hey—that’s exactly why NRVTA is here. Whether you’re learning the ropes, planning upgrades, or exploring a career as an RV technician, we’ve got the tools, training, and support to get you there.
Got a question? Drop it in the comments or come see us in class.
Until next time—stay cool out there!