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How To Check The Ammonia Level In RV Fridge?

Written by Philip Lopez / Fact checked by Paul Lemaire

how to check the ammonia level in rv fridge

RV fridges usually use ammonia as a refrigerant because it’s very efficient and safe for the ozone layer. Ammonia evaporates to cool the fridge, and it should be pure and water-free to keep things cold. However, ammonia might leak and cause health hazards, so you need to learn how to check the ammonia level in RV fridge efficiently.

If you don’t know where to start, here are several methods of checking the ammonia level in your RV fridge.

Table of Contents

Method 1: Ammonia Detector


The most efficient way to check the ammonia level in your RV fridge is to use an instrument, like an ammonia detector. This method is also more reliable because it shows the exact amount of ammonia release.

What You’ll Need

  • Ammonia Detector

An RV fridge uses ammonia and sodium chromite as coolants. An ammonia detector can help determine whether the coolant is functioning correctly or not. The said detector will check the levels to determine whether ammonia is leaking from your RV fridge.

Selecting the suitable ammonia sensor depends on the location, concentrations, and other factors. For RV fridges, a low concentration range detector can offer an ideal resolution and precision. In addition, these devices set off visual, audible, or vibrating alarms to warn you that ammonia is leaking.

Step-By-Step Instructions

  • Install The Ammonia Detector

The best place to install the ammonia detector is near the ceiling because ammonia is lighter than air. Make sure it’s in an area with good airflow and near the gas source for early detection. As much as possible, keep the instrument away from ventilation fans and dead air spots.

For this instance, above the fridge’s compressor is ideal. You can also install it around five feet above the floor and within a 30 feet range of possible leaks.

  • Take Heed For The Signs

Ammonia detectors may light or sound an alarm to tell you that an unhealthy amount of ammonia is present in the air.

Once the instrument detects an ammonia leak, it’s also a sign that your coolant level is down. The only way to solve an ammonia leak is to replace the RV fridge entirely.

Method 2: Phenolphthalein Test Strip

An inexpensive way to determine the small ammonia leaks in your RV fridge is to use a phenolphthalein test paper. While this method can determine the ammonia gas in the air, it’s not quantitative.

What You’ll Need

  • Phenolphthalein Paper

This filter paper is often used to indicate acid-base titrations. As a weak acid itself, phenolphthalein changes color from white to pink when it detects ammonia in the air. Phenolphthalein can spot ammonia gas in the air because it has a ph level of 11.6.

These strips often come in a vial to preserve their effectiveness. They have a white color which changes when it detects ammonia vapors in the air. To store the rest of the strips, keep the vial in a cool, dry place.

  • Water

You might need water to wet the test strip. The test strip turns colorless when wet in water, and it helps the ammonia gas to get dissolved into the wet strip easily. Though any type of water is suitable, I prefer to use distilled water because it has no impurities.

A small amount of water will do in this litmus paper ammonia detection test. For more convenience, use tap running water but make sure that you don’t oversoak the paper.

Step-By-Step Instructions

  • Wet The Test Strip

First, remove a piece of phenolphthalein test strip from the vial carefully. Avoid touching the strip anywhere other than the part where you hold it with your fingertips to ensure efficiency.

Now, wet it with distilled water to let the ammonia gas dissolve into the wet strip. You can wet it directly from tap water or dip it in a glass of water.

  • Move Your Litmus Paper Around

Hold your litmus paper and move it around your RV fridge. Then, move it near the compressor and inside the box. Since ammonia gas floats higher than air, move the litmus paper near the ceiling.

If the litmus paper turns pink or fuchsia, then that indicates an ammonia leak. If not, then there’s no ammonia leak in your RV fridge.

Method 3: Sulfur Stick


This method is the same as the above, except that it uses a sulfur stick instead of phenolphthalein paper. While this method is effective, you need to be extra careful in holding a burning stick.

What You’ll Need

  • Sulfur Stick

Sulfur stick is made from a wick containing sulfur particles and used to determine minor ammonia leaks. Sulfur sticks light up and glow, similar to a taper that’s used to ignite fireworks. The color of the smoke is used to indicate the ammonia leak.

Sulfur sticks are often stored in water-tight tubes. It would be best if you didn’t get them wet, or else they won’t ignite properly. I think they’re cost-effective because a tube contains about 100 sticks for long-term use.

  • Match Or Lighter

Obviously, the match will be used to light the sulfur stick. You can use any brand of match you like, as long as it lights up properly. Matches are better than lighters because they’re more environment-friendly and simple to use.

However, if you want a quick light, a lighter is more suitable. You can use a lighter with one hand while you hold the sulfur stick on another. My only dislike of lighters is that they don’t seem to work properly in frigid temperatures.

Step-By-Step Instructions

  • Light The Sulfur Stick

Get a sulfur stick from the tube and hold the part opposite the wick. Using a match or lighter, light the stick. The wick should glow like the smoldering stick used for fireworks.

It’s more convenient to use a lighter because you can hold the stick with one hand and use the lighter in another hand. If you use a match, you can ask another person to light it as you hold the stick.

  • Move It Around

Once the sulfur stick starts to light, move close to the RV fridge slowly. Move the stick near the compressor or inside the box. Watch for any changes.

If the sulfur stick starts to release white smoke, then it indicates an ammonia leak. If not, then you’re safe from any ammonia leaks.

Method 4: Use Your Senses

You can also check for possible ammonia leaks without the use of any tools or materials. In this method, you only need to rely on your sense of smell and hearing. However, this method might not be as reliable as the others above.

Step-By-Step Instructions

  • Smell Inside The Box

Luckily, ammonia has a strong odor that’s easy to identify. To check for ammonia leaks manually, smell inside the box. If you notice a strong ammonia odor, then it means a leak in the evaporator region.

The pungent odor may be gone if your fridge has leaked for a long time. However, you’ll probably hear a gurgling sound from the refrigerator’s back several minutes after turning it on.

  • Check Heat

For the RV fridge to work properly, the coils should be heated to make the coolant flow through the tubes properly. If you observe that the heat is uneven, then there’s probably not enough coolant to run through the tubes. A great indicator is when you feel that one area of the coil is extremely hot.


The RV fridge is probably one of the essential appliances for comfortable traveling, so you should keep it in good condition. Since these refrigeration units run with ammonia, make sure that you know how to check the ammonia level in RV fridge properly. Fortunately, all of the methods I presented above are easy.

If you want the most reliable instrument to check for ammonia leaks, use an ammonia detector instrument. For quick, inexpensive methods, try litmus paper and sulfur sticks.

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