RV Furnace And AC Run At The Same Time | How I Identify and Solve the Issue

As an RV owner, I know that both the furnace and air conditioner are critical for maintaining a comfortable temperature inside your home on wheels. RV furnaces distribute heated air through ductwork, usually powered by propane or diesel fuel. Air conditioning units electrically cool and dehumidify the indoor air. With fluctuating outdoor temperatures, you may find both appliances running at the same time. 

This article will help you understand why this happens and how to troubleshoot any issues.

RV Furnace And AC Run At The Same TimeRV Furnace And AC Run At The Same Time

Reasons When Both Furnace and AC Run at the Same Time

In most cases, it’s actually just the fan inside your AC that runs along with the furnace – the compressor usually does not turn on unless active cooling is needed. There are a few different reasons you may experience both the furnace and AC fan operating:

Improved Air Circulation

The AC fan helps circulate the hot air from the furnace around your RV. This maintains a consistent temperature and prevents cool spots from developing.

Reduced Noise

The constant humming of the AC fan can help mask some of the loud cycling of the furnace turning on and off. This white noise effect provides a nicer ambient environment.


If you are camping in a humid environment, the AC fan helps remove moisture from the indoor air as it circulates. The furnace then reheats the air to the desired temperature.

Heat Pumps

Heat Pumps

Some RVs utilize air-source heat pumps, which provide both heating and cooling from the same system. When in heat pump mode, it runs as a single unified appliance with integrated functions.

How to Identify Why RV Furnace and AC Running at the Same Time?

If you notice both the furnace and AC running simultaneously, the first step is confirming that it is in fact just the AC fan. Feel the air vents to check that hot air continues flowing out while the AC vents blow room temperature or slightly cool air. If the AC compressor was activated, very cold air would be blowing.

Check your thermostat settings as well. Most issues arise from accidentally setting the fan to HIGH or LOW rather than AUTO. This makes the fan run continuously regardless of heating or cooling needs. Ensure the mode is set properly to FURNACE if calling for heat.

How to Troubleshoot RV Furnace And AC Run At The Same Time?

If you are experiencing issues with simultaneous furnace and AC operation, here are some troubleshooting tips:

Adjust Thermostat Settings

Adjust Thermostat Settings

Double-check that the fan is set to AUTO and the mode corresponds to HEAT when using the furnace. An outdated or malfunctioning thermostat may require replacement.

Install a Heat Pump

Converting to an integrated heat pump system provides more unified heating and cooling operation. This minimizes redundant appliance use.

Power Management

Be mindful of energy consumption from running dual systems. When possible, utilize shore power or a generator and turn off any other unnecessary electric appliances.

Benefits of Running Both AC and Furnace

While it may seem counterproductive at first, operating both the furnace and AC fan concurrently has some advantages:

  • Balanced Temperatures

The dual airflow allows you to maintain a comfortable ambient temperature in your RV space despite fluctuations in the weather outside.

  • Utilize Existing Infrastructure

Since the furnace and AC share connected ductwork, managing the two systems together leverages these existing channels to efficiently distribute hot, cold, and neutral-temperature air.

Potential Consequences of Simultaneous Operation

However, there are also some downsides to consider when frequently running both appliances:

Increased Power Consumption

The combined electrical load of the furnace and AC fan can drain your RV batteries faster or increase costs if running on shore power.

Premature System Wear

The excess run time accelerates wear and tear on the furnace, AC, thermostat, and other components. This may reduce lifespan and require earlier replacement.

Heating Inefficiency

Blowing cold air over the furnace’s hot coils counteracts heating efforts and leads to longer run times to reach the set temperature.

FAQs with Answers

Here are answers to some frequently asked questions about RV heating and cooling:

  • Is it safe to run my furnace and AC at the same time?

Yes, RV climate systems are designed to accommodate simultaneous furnace and AC fan operation. This is normal in certain conditions. However, extended dual usage can overwork components and lead to faster breakdowns.

  • Does this waste a lot of energy?

Running both the furnace and AC fan simultaneously consumes more power. Regularly monitor your battery levels and manage electrical loads to maximize efficiency.

  • Why does my AC keep turning on when using my furnace?

If only the AC fan activates along with the furnace, check your thermostat setting to ensure the fan is set to AUTO. A control board failure can also cause this. Have an RV technician diagnose potential system faults.

Parting Notes

I hope this guide gave you a comprehensive understanding of RV furnaces and air conditioners working in tandem. While counterintuitive, this simultaneous operation does serve important circulation and humidity control functions. Be sure to monitor your climate system during use and adjust settings or troubleshoot any persistent issues promptly to maintain optimal performance. Your certified RV technician can also help keep both heating and cooling units in peak condition.

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