Do RV Air Conditioners Have Capacitors?

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If an air conditioner isn’t working, the capacitors are some of the first devices to check. But first, do RV air conditioners have capacitors?

RV air conditioning systems use 2 capacitors. Each capacitor unit contains a start capacitor and a run capacitor. One is for when the engine starts and the second for when the engine is running.

Problems with any of these devices can cause the RV air conditioner to malfunction or not work at all. And this can lead to long-term damage to the compressor. However, before seeing how to test your air conditioner’s capacitors, let’s see what their functions are.

What Is The Function Of The Capacitor?

The capacitor is present in most of our household and vehicle appliances. But what is it for exactly?

The air conditioner has a motor to run. The motor is very often a conventional winding motor. For the motor to start and maintain itself, it needs a boost: this is where the capacitor comes in!

The capacitor is a chemical component. It stores the current that is injected into it and restores it so that the motor can start.

In addition to its starting aid, the capacitor helps maintain engine torque. And yes, depending on the load, the motor may have difficulty deploying enough force. The capacitor stabilizes the supply current and occasionally transmits voltage to maintain the motor torque whatever the load.

How Do I Test The Capacitors On My Air Conditioner?

Do you need to know if the capacitor in your air conditioner is defective? Before replacing it, it must be tested! Below, we will see the steps to check its condition.

Preparations To Be Made

First of all, you must determine the location of your AC capacitor. It is usually very close to and connected to the motor. Of cylindrical shape, it can be made of plastic or aluminum. Don’t forget to take a photo of the circuit before disconnecting your capacitor! This will help you when reassembling or installing new capacitors.

What Materials Do I Need To Test My Capacitor?

  • A multimeter that you put in the Ohmmeter position (Ω symbol)
  • Insulated screwdriver
  • Insulating gloves

Step 1: Turn Off The Circuit Breakers Running The AC

Turn off the circuit breakers that run the air conditioner. This is located in the electric load center of the RV. Then you have to remove the AC connection’s shore power to the RV.

Do not touch the connectors with your hands before doing this manipulation! We advise you to wear insulating gloves because the capacitor may still be charged and may give you an electrical shock.

This can be very unpleasant and dangerous if you have a pacemaker.

Step 2: Climb The RV Roof And Locate The Capacitors’ Enclosure

After climbing the RV roof to where the AC unit is housed, unscrew the head screws and find the start and motor run capacitors.

Step 3: Calibrate The Multimeter And Perform The Test

Set your multimeter to the Ohmmeter function. This makes it possible to check the continuity of a conductor, here, the continuity of your capacitor.

Place the tips of your tester on each terminal of the capacitor.

Step 4: Repeat The Operation By Reversing The Tips Of The Tester On The Terminals Of The Capacitors

You will observe that the values displayed on your tester increase until they stabilize. Now reverse the peaks: you will observe that the values drop until they are stabilized. Or vice versa depending on the placement of the tips!

The principle is to see if the capacitor charges and discharges. If the tester is sending a very low current, the operation can be repeated several times.

Step 5: Interpret The Measurement

If by reversing the tips of the tester, you manage to obtain rising then falling values (Step 3), this means that the capacitors are working correctly.

If, on the contrary, the capacitor(s) do not charge or discharge, they are therefore defective and will have to be replaced.

Extra Tips

  • Some air conditioners in older RVs have a driving part: pulley, belt, gear. This sometimes makes it easier to determine if the capacitor is defective. Be careful not to get your fingers caught!
  • The principle is simple: Switch on the device and if you hear the motor forcing, growling, or purring, turn the pulley or the shaft of the gear. If the motor starts to run, there is a high probability that the capacitor will need to be changed.

How Do I Know If My RV AC Capacitor Is Bad?

When this capacitor is faulty, the signs generally observed on your AC are:

  • The air conditioner has a problem running or no longer runs
  • The air conditioner may be turning off on its own
  • The AC could be making a humming noise
  • AC no longer blowing cold air
  • High energy consumption

The capacitor could be the cause because it does not give the necessary impulse to the AC for it to function correctly. If you notice these signs, then it is better to test the capacitor.

How Do You Install A Hard Start Capacitor On An RV Air Conditioner?

If you’ve discovered a faulty start capacitor and decided to replace it, the procedure is simple.

  • Get a screwdriver, zip ties, and a clear silicone adhesive. Go up the roof, remove the protective cover of the AC. Then remove the screws of the access panel and find the run capacitor to which you’ll connect the hard start capacitor.
  • The wire on the hard start capacitor which connects to the PTCR will go to the same connector which is the red wire while the second wire will go to the yellow wire.
  • When the electrical connection is done, all’s left is to have the hard start capacitor mounted. You can hold them in place with the adhesive and use the zip ties to hold up the wires.


RV AC’s have capacitors. When your RV’s AC isn’t working, you should check if they are still good. Testing a capacitor saves money by alerting you to replace it as soon as it is faulty.

This is inexpensive compared to having to replace the capacitor. You now know all the steps necessary to easily and safely test the capacitor of the RV AC. We hope this tutorial will help you determine the condition of your capacitor for yourself.

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