RV AC compressor

Troubleshooting RV Air Conditioner Compressor NOT Coming On

Chris Coleman

Any problem with the air conditioning system in the RV is annoying, stressful, and uncomfortable. Imagine you have camped in a campsite in Arizona or California during the peak summer days, and the AC in your motorhome is not working. It will literally feel like living in hell. One common problem is the RV air conditioner compressor not coming on. We are going to discuss what causes this problem and how you can troubleshoot it.

How Does the AC System Work?

To understand any problem with the air conditioning system, it is better to have an idea of how the system works.

The AC system in your RV is combined with the heating system. There are two main components, a compressor and a fan. The first one circulates a refrigerant, such as Freon, through the condenser’s coils and fins. The fan, on the other hand, blows cold air across the RV.

A thermostat turns the compressor and fan on and off. Other components required for that on/off mechanism is a thermometer and capacitor(s). A 12-volt electrical system supplies power to these parts.

RV air conditioner compressor
The AC system in your RV is combined with the heating system.

RV AC Compressor Not Starting: How Does the Problem Look Like?

How do you know that the compressor in your RV AC is defective? When you switch the air conditioning on, it cannot function properly because the compressor shuts down. Only the fan blows, but the vehicle’s interior won’t be cold due to the non-circulation of the cooling fluid.

If you run the AC off the generator, a defective compressor is likely to stall the generator.

ac compressor not coming on
AC blows hot air when the compressor is faulty.

The Causes of RV Air Conditioner Compressor Not Coming On

There could be several reasons for the compressor to act up. A malfunctioning starting capacitor is likely to be the most common culprit.

The symptoms of a bad capacitor are:

  • The air conditioning system creates a humming sound and tries to start but cannot.
  • The system runs a few minutes and then stops after tripping off a breaker.
  • You need to give a push to the fan to start it.
  • Air conditioner blows hot air because the compressor does not function.

What does the capacitor do? It stores some electric power to boost the compressor and fan motor when you switch on the AC unit. That little push is vital for the motor to kick off.

A bad capacitor may sometimes explode without damaging any other parts of the system. It may become faulty when you leave the motorhome unused for a long period. Looking like a small battery or button, an air conditioning system may have one or more than one capacitor. If there is only one, both fan and compressor won’t function when the capacitor becomes defective.

How to Examine the Capacitor?

When the RV air conditioner compressor not coming on or you see any of those symptoms, you must check the capacitor(s) for any possible defect.

Using a multimeter is the easiest way to examine the capacitor’s condition. When you connect the multimeter’s probes to a good capacitor’s prongs, the display will show a random value that decreases slowly over time. This won’t happen when the capacitor is defective.

Replacing the bad capacitor is the simplest and safest solution to make the AC functional. The new one’s model number and voltage should be the same as the old one.

A Few Other Components to Check

When the AC compressor not coming on, a few other components besides the capacitor can be the culprits.

Start Relays

Malfunctioning relays can cause the same trouble. The only way to be sure is to replace them with new ones. If the compressor works after the installation, your problem is solved.

Valves

A broken valve directly affects the functionality of a compressor. The most common issue is that the refrigerant gets to the compressor inlet in a liquid form instead of gaseous. Replacing the bad valve will be enough to restore the compressor’s normal operation.

What to Do When the Compressor Is Bad?

If the AC still does not function smoothly after changing the capacitor, you are probably dealing with a bad compressor. When this component is working fine, it creates an audible sound and feels warm to touch. A bad compressor means that the fan will blow only hot air. Sometimes, the component can leak oil or discharge smoke.

When the RV air conditioner compressor not coming on, a clamp-on ammeter is a perfect tool to check its health. The compressor has an ampere rating and the reading on the ammeter should not cross that number. If it does, the compressor is toast.

rv ac compressor not starting
Examine the compressor with a clamp-on ammeter.

If you are sure that a bad compressor is a reason the AC is not working or blowing hot air, you have to change this component. Unless you find a functional used unit, repairing the compressor is too expensive.

If you want to avoid the problem of the RV air conditioner compressor not coming on, the first thing to do is to purchase a good RV AC system. These units are better choices if you want to ensure comfort in your next RV vacation. They will hold up in extreme heat and their components will not break down so easily.

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