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If your RV AC compressor keeps shutting off while the fan continues running, it does not automatically mean your air conditioner has failed. Some compressor cycling is part of normal operation. However, when the compressor begins shutting off more frequently, especially during the hottest part of summer, it can be an indication that something needs attention.
In this Tech Tip Tuesday, Todd explains several reasons an RV air conditioner compressor may cycle off and what RV owners should check when it begins happening more often.
Why Does an RV AC Compressor Cycle Off?
There are situations where the compressor cycling off is normal.
One reason involves airflow across the evaporator coils. Your air conditioner has a temperature sensor associated with the evaporator coils. If there is not sufficient airflow, the coils can become too cold.
Warm, moist air moving across coils that are too cold can lead to freezing. That freezing can further restrict airflow.
The air conditioner uses a temperature sensor to help prevent this situation. When necessary, the system can turn the compressor off. This means hearing the compressor cycle off while the fan continues running is not automatically an indication of a problem.
The concern is when the RV AC compressor keeps shutting off more frequently even though the RV is still hot.
Low Voltage Can Cause the Compressor to Get Too Hot
During the hottest days of summer, an RV air conditioner compressor has to work hard. As the compressor works, it produces heat.
The compressor has overload protection designed to protect it when temperatures become too high. Depending on the compressor, this protection may be located on the outside or inside.
One reason the compressor can become too hot is low voltage.
When staying at an RV park, the power being delivered to your RV may not always be ideal. Todd explains that the compressor is designed to operate at a certain RPM. At the proper voltage, it consumes the appropriate amount of amperage.
When voltage drops, the compressor can consume more amperage. That additional amperage creates more heat.
If the compressor case becomes too hot, the overload protection can open and prevent 120 volt power from entering the compressor.
This is one reason understanding your RV electrical systems and the power being delivered to your RV is important.
An EMS Does Not Eliminate the Possibility of Low Voltage
Todd also points out that having an EMS does not necessarily eliminate low voltage as a possible cause.
An EMS may allow power to continue flowing at a voltage that is still low enough to cause the compressor to run hotter. Todd specifically discusses an EMS that allows voltage as low as 103 volts.
The air conditioner may still operate, but the lower voltage can cause the compressor to pull more amperage and produce additional heat.
If the RV AC compressor keeps shutting off, Todd recommends checking the voltage coming from the pedestal as part of the troubleshooting process.
Dirty Coils Can Make Your RV AC Compressor Work Harder
Voltage is not the only thing to check.
Airflow and clean coils are also important.
If the condenser coils cannot properly reject heat, pressure continues to build within the refrigerant system. The compressor then has to work harder.
Working harder means drawing more amperage, which creates additional heat.
The evaporator side also needs sufficient airflow. If the coils become clogged and begin freezing, that can also affect operation.
This is why Todd recommends getting your eyes on the air conditioner and checking the coils rather than immediately assuming the compressor itself has failed.
Understanding how an RV air conditioner works can make it easier to recognize why airflow, heat rejection and voltage all matter.
When Is Compressor Cycling a Warning Sign?
Some cycling is normal, even when the fan continues running and the RV has not yet reached the desired temperature.
The important thing is to pay attention to how frequently it happens.
Todd gives the example of a compressor that runs for five minutes, shuts off, then runs for another five minutes and shuts off again.
When the compressor begins cycling more and more often, Todd describes that as a telltale sign that there is a problem that needs to be investigated.
Possible causes discussed in this Tech Tip include clogged coils on the evaporator side, clogged coils on the condenser side and low incoming voltage.
What Should You Check When Your RV AC Compressor Keeps Shutting Off?
Todd recommends starting with two basic areas.
First, inspect the coils and make sure they are clean. You want proper airflow across the evaporator coils and proper heat rejection from the condenser coils.
Second, check the voltage coming from the campground pedestal.
These checks can help determine whether airflow, heat rejection or low voltage may be contributing to the compressor becoming too hot and activating its overload protection.
For RV owners who want to better understand systems like these, RV Fundamentals Training provides an opportunity to learn more about how the systems in an RV operate.
For those interested in developing their skills further and becoming an RV technician, RV Service Technician training at the National RV Training Academy provides additional hands-on education.
As Todd says at the end of this Tech Tip, whether you want to better understand your own RV or are interested in becoming a technician, learning how these systems work is the first step.
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