Freon volume in the Nissan Murano air conditioner: complete technical information

The air conditioning system is one of the busiest components in a car. Nissan Murano, especially in hot climates. Maintaining the correct refrigerant pressure is critical not only to a comfortable cabin temperature, but also to the longevity of the compressor and evaporator itself. Many crossover owners are faced with a situation where the cold becomes less, but they do not know how to correctly diagnose the problem and exactly what volume of freon is provided by the manufacturer.

Misconceptions that “the more freon, the better” often lead to serious damage. Excessive pressure causes the system to overheat, and insufficient pressure causes the compressor to run dry. In this article we will analyze in detail the technical characteristics of the gas station for all generations. Nissan Murano, verification methods and nuances that are often missed during self-service.

Technical standards for refueling for different generations

Manufacturer Nissan sets strict standards for refrigerant volume, which vary depending on the year of manufacture and body modification. For the first generation Murano (Z50), produced from 2002 to 2007, the standard volume is 550-600 grams. However, the exact value is always indicated on an information plate located under the hood, usually in the radiator area or on the inside of the hood.

The second generation (Z51) and third generation (Z52) have similar requirements, but may differ depending on the type of climate system (single-zone or two- and three-zone). In systems with a rear evaporator, the filling volume increases by 100-150 grams. Never rely solely on the year of manufacture, as changes to the circuit design may have been made in the middle of the model cycle.

• 🔹 Nissan Murano Z50: main volume of R134a - 550 g (±20 g).
• 🔹 Nissan Murano Z51: volume varies from 600 g to 750 g depending on the configuration.
• 🔹 Nissan Murano Z52: Requires precise dosage, usually 650-700 g for a standard system.

Using the wrong amount of refrigerant interferes with heat transfer. If there is a shortage of freon, the oil does not return to the compressor, which leads to its jamming. When an overflow occurs, the pressure in the system reaches critical values, and the emergency valve is activated or the lines rupture.

⚠️ Attention: The plate under the hood indicates the weight of the R134a refrigerant in grams, not the pressure in atmospheres. Do not confuse these parameters when working with a pressure gauge station.

Refrigerant and system oil markings

Modern air conditioning systems Nissan Murano use refrigerant type R134a. This is standard for most vehicles manufactured after 1995. Despite the appearance of the new R1234yf freon, it has not yet found widespread use in crossovers Nissan, so when servicing old and new models you will be dealing with R134a.

A critical parameter is the type of compressor oil. For systems with R134a freon, synthetic oil of the class PAG 46 or PAG 100. There is no interchangeability of oils: mixing mineral oil with PAG oil will lead to the formation of sludge and system failure. When the system is fully charged, the oil is already contained in the freon in the form of an emulsion, but when replacing the compressor, its amount must be dosed separately.

• 🔹 Refrigerant type: R134a (tetrafluoroethane).
• 🔹Oil type: PAG 46 (for most models) or PAG 100 (for high pressure systems).
• 🔹 Freon color: colorless (if there is a leak, a fluorescent additive is often added).

It is important to consider that when replacing components such as the condenser or evaporator, some oil remains in the system. You need to know how much oil was in the old unit and add the missing amount to the new circuit. This is often ignored, leading to oil starvation.

⚠️ Attention: If you see the R12 marking on the plate, do not under any circumstances try to fill the R134a system without completely flushing and changing the oil, as these are different chemical environments.

Diagnostic and vacuum procedure

Before any refueling, it is necessary to conduct a thorough diagnosis. You can’t just add freon “by eye”. First, the system is evacuated to remove moisture and air. Humidity is the main enemy of air conditioner as it forms acid and ice in the capillary tube. The vacuum process should last at least 30-40 minutes when using a high-quality pump.

After evacuation, the system is left under vacuum for 10-15 minutes. If the pressure gauge needle begins to rise, this indicates a leak. In this case, refilling is pointless; you need to look for a leak with a soap solution or a leak detector. Only after confirmation of tightness can you begin refueling.

• 🔹 Use only high-quality vacuum oil for the pump.
• 🔹 Monitor the ambient temperature as it affects pressure.
• 🔹 Turn off the compressor (AC Clutch) during vacuuming.

Freon filling sequence

The system is charged through the lower low pressure port. Never connect a hose to the high pressure port while the engine is running, as this is dangerous to your health and equipment. Freon is charged in liquid form through the bottom manifold, but the cylinder itself must be upside down if you are using liquid refrigerant, or upside down for gas, depending on the type of cylinder.

The refueling process requires control of the scales. Electronic scales must be installed under the cylinder. Turn on the engine, air conditioning at maximum (MAX A/C) and blowing at medium speed. Slowly open the valve on the pressure gauge station, adding freon in small portions.

Monitor the low pressure gauge. For Nissan Murano at an air temperature of +25°C, the normal pressure in the low pressure circuit is 2.5–3.5 bar. High pressure should be in the range of 14–18 bar. Exceeding these limits indicates problems with the system or incorrect charge volume.

Порядок подключения:
1. Подключить синий шланг к порту Low (низкое давление).
2. Подключить красный шланг к порту High (высокое давление).
3. Убедиться, что центральный шланг подключен к баллону с фреоном.
4. Открыть вентиль на баллоне и стравить воздух из шланга.

⚠️ Attention: Charging liquid freon through the high pressure port while the compressor is running can lead to water hammer and destruction of the compressor valves. Refill only through the low pressure port.

What happens if you overfill freon?

When freon is overfilled, the pressure in the system increases sharply. This causes the safety valve to operate, releasing freon into the atmosphere and possible damage to the pipes. In addition, liquid freon can enter the compressor, causing water hammer, which instantly disables the unit. Overflow diagnostics is carried out by increased pressure on both pressure gauges and the absence of cold air at the outlet of the deflectors.-->

Table of pressure depending on temperature

To fine-tune the air conditioner, it is not enough to know only the weight of the freon. The pressure in the system directly depends on the ambient temperature. The table below will help you evaluate system performance under different conditions. Please remember that these values are indicative and may vary slightly for each specific model. Murano.

Air temperature (°C)	Low circuit pressure (bar)	High circuit pressure (bar)	Outlet temperature (°C)
+20	2.0 - 2.5	12.0 - 14.0	+4 ... +6
+25	2.5 - 3.0	14.0 - 16.0	+2 ... +5
+30	3.0 - 3.5	16.0 - 18.0	+1 ... +4
+35	3.5 - 4.0	18.0 - 20.0	+0 ... +3

If the pressure of the low circuit is below normal, this indicates a lack of freon or a clogged filter drier. If the pressure is high, there may be air in the system or the condenser is dirty. In such cases, simple topping up will not help; a full diagnosis will be required.

FAQ: Frequently asked questions

How can I find out the exact amount of freon for my Nissan Murano?

The exact volume is indicated on the information plate under the hood, usually in the form of the inscription “REFRIGERANT: XXX g R134a”. If the plate is missing, refer to the official specifications for your model and year.

Is it possible to add freon without vacuuming?

If you are simply adding a small amount to compensate for natural leakage and the system is sealed, vacuuming is not required. But when fully refueling or repairing, vacuuming is mandatory to remove moisture.

Why does the air conditioner stop cooling even though there is enough freon?

This may be due to a faulty compressor, a clogged condenser, a non-working radiator fan, or a broken pressure sensor. A complete system diagnostic is required.

How often should you check the freon level?

It is recommended to check the system every 1-2 years, especially before the start of the summer season. This will allow you to detect micro-leaks in time and prevent serious damage.