Climate control system in a crossover Nissan Murano is one of the key elements of comfort, especially in the hot season. When the air conditioner stops blowing cold air, many owners immediately suspect a freon leak or a compressor failure, but the root cause often lies in a much simpler and cheaper element - the control relay.
Malfunction air conditioner relay can manifest itself in different ways: from a complete lack of operation of the radiator fan to the fact that the compressor does not turn on at all, despite a working electrical circuit. In cars Nissan Murano second and third generation (Z50, Z51) relays are often integrated into the fuse box or made as a separate module, access to which requires care.
Understanding the operating principle of this device and the ability to carry out initial diagnostics will allow you to save a significant amount on a visit to the service center. In this article we will look in detail at how to identify the problem and check control circuit and correctly replace the failed unit, restoring the functionality of the cooling system.
How the relay works in the Murano climate system
The air conditioning relay is an electromechanical switch that supplies high voltage to consumers (compressor, radiator fans) upon command from the engine control unit or climate control unit. Unlike simple fuses, a relay is capable of switching large currents required to start powerful system components.
In the car Nissan Murano The relay performs a critical protection function. It isolates the low-current control circuit (from the ECU) from the high-current power circuit. When you press the button A/C on the panel, the signal enters the relay coil, the magnetic field closes the contacts, and current begins to flow to air conditioning compressor.
If the contacts inside the relay burn out or the coil loses its magnetic properties, the circuit breaks. In this case, the system may behave unstable: sometimes the cooling works, sometimes it doesn’t, or the radiator fan turns on at maximum power constantly, trying to compensate for the overheating of the system. Understanding this logic will help you differentiate between a faulty relay and a problem with the pressure sensors.
It is worth noting that on some modifications Murano used smart relay, which has built-in overload protection. If there is a short circuit, it can block the supply of voltage until the cause of the failure is eliminated or the error is reset through the diagnostic scanner.
⚠️ Attention: Do not try to forcefully close the relay contacts with a screwdriver or jumper without first checking! This may cause the engine ECU to fail or cause a fire in the wiring in the engine compartment. Nissan Murano.
Typical symptoms of a malfunction
A problem with a relay can be determined by a number of specific signs that are not always obvious to an inexperienced driver. The most common symptom is when, when you turn on the air conditioner, you hear a characteristic click under the hood, but no cold air comes out. This indicates that the relay control is working, but the power circuit does not close due to burnt contacts.
Another scenario is the absence of a click at all. In this case, the problem may be either in the relay itself (the coil is faulty) or in the control signal from the control unit. It is important to check if it works cooling fan when the air conditioner is turned on. If the fan does not start and the light A/C lights up, there is a 90% probability that the fault is in the fan relay or compressor relay.
Sometimes the malfunction manifests itself in the form of intermittent failures: the air conditioner works normally at idle, but turns off when driving, or vice versa. This may indicate oxidation of the contacts inside the relay housing or a violation of the thermal operating conditions of the device.
Also pay attention to strange sounds. If you hear a buzzing or crackling noise coming from under the dash or from the fuse box, this is a sure sign that the relay is trying to turn on, but the contacts are sticking or unable to close. In this case, the operation of the car Nissan Murano with the air conditioner turned on can lead to complete failure of the entire electrical circuit.
- 🔊 No relay click when the button is turned on
A/Con the panel. - 🌡️ The compressor does not turn on, although the system is charged with freon and the sensors are working properly.
- 💡 The radiator fan does not start when the air conditioner is operating.
- ⚡ The fuse trips immediately after an attempt to turn on the cooling system.
- No relay click
- There is a click, but there is no cold
- Fan doesn't work
- Intermittent crashes
Diagnostics and testing of relays in the fuse box
The first step in diagnosis is to visually inspect and test the relays in the fuse box. On models Nissan Murano Z50 and Z51 the main unit is usually located in the engine compartment, next to the battery, and the additional unit is located in the passenger compartment on the driver's side. You will need a service manual or fuse diagram to find the exact A/C relay.
Find the relay marked AC RELAY or COMP RELAY. Carefully remove it from the socket without using excessive force to avoid damaging the contacts. Inspect the housing for cracks, signs of melting, or a burning smell. If the case is deformed from overheating, replacement is required.
Use a multimeter to check functionality. Set the device to resistance measurement mode (Ohms) and measure the resistance at the control pins (usually pins 85 and 86). The normal value is between 60 and 120 ohms. If the multimeter shows open (infinity) or zero, the relay is faulty.
Next, check the power contacts. Apply 12 volts from the battery to the control terminals. You should hear a clear click. Then check the circuit between the power terminals (30 and 87) - the multimeter should show resistance close to zero. If the contacts do not close, the relay must be replaced.
⚠️ Attention: When testing a relay with a multimeter, be sure to disconnect the negative terminal of the battery before removing the fuse box if access to it is difficult and there is a risk of accidental shorting.
Step-by-step replacement instructions
The process of replacing the air conditioner relay with Nissan Murano does not require complex special tools and can be done by any car enthusiast. The main thing is to follow the sequence of actions and safety precautions. Start by preparing your work area: open the hood, make sure the engine is off and the ignition key is removed.
Remove the fuse box cover in the engine compartment. Find the correct relay using the diagram on the inside of the cover. Pull the relay out of the socket using a special grip (if available) or carefully prying it with an insulated screwdriver.
Before installing a new relay, make sure that its type and characteristics are exactly the same as the old one. Pay attention to the location of the contacts - even if they look the same, the connection diagram may differ for different modifications Murano. Insert the new relay until you hear a characteristic click, making sure it is a tight fit.
After installation, check the system operation. Turn on the ignition, start the engine and activate the air conditioning. Listen to the relay and check if cold air is coming out of the deflectors. If the system works, the problem is solved. If not, a more in-depth diagnosis of the electrical wiring is required.
☑️ Preparing to replace the relay
What to do if the relay socket is oxidized?
If the contacts in the fuse block socket itself are oxidized or bent, simply replacing the relay will not help. It is necessary to carefully straighten the contacts with thin tweezers and clean them with alcohol or a special contact spray. In advanced cases, it may be necessary to replace the entire fuse box or solder new contacts, which is best left to an auto electrician.
Before purchasing a new relay, be sure to take a photo of the old element to make sure that the contact numbering and housing shape match. Often different markets (Japan, USA, Europe) use different versions of the same nodes.
Selection of original spare parts and analogues
When selecting a part for Nissan Murano It is important to understand the difference between original components and high-quality analogues. The original relay is marked Nissan and catalog number, which can be found in spare parts catalogs. This guarantees compliance with all electrical parameters and durability of the materials.
However, original parts are often expensive. There are proven analogue manufacturers on the market, such as Denso, Hella or Bosch, which produce relays with similar characteristics. These brands are often suppliers to the assembly line, so their products are not inferior in quality to the original, but are cheaper.
Avoid buying cheap nameless relays from markets or unverified stores. Poor quality contacts can quickly oxidize, and the coil may not withstand operating currents, leading to repeated failure and potential fire. Savings of 500 rubles can result in replacing the fuse box for several thousand.
Pay attention to the packaging. A good manufacturer always indicates the date of production, country and certification. If the relay is sold simply in a package without markings, the risk of running into a fake increases many times over. For crossover Murano with its complex electronics, the quality of the electrical components is of utmost importance.
| Relay type | Approximate catalog number | Compatibility | Average price (RUB) |
|---|---|---|---|
| Original Nissan | 25230-1AA0A / 25230-1AA1A | Murano Z50, Z51 | 3500 - 5000 |
| Analogue Denso | DR-1204 | All Murano generations | 1800 - 2500 |
| Similar to Hella | 4RD 008 540 | Murano Z50, Z51 | 1500 - 2200 |
| Budget analogue | Various brands | Risk of non-compliance | 400 - 800 |
An original relay or a high-quality analogue from a well-known brand (Denso, Hella) is an investment in reliability, which pays off in the absence of repeated breakdowns and risks to the wiring.
Features of the Murano Z50 and Z51 electrical circuit
Electrical diagram Nissan Murano The first generation (Z50) differs from the scheme of the second generation (Z51) and third (Z52). On the Z50, the A/C relay is often combined with the radiator fan relay into a single unit, making diagnostics more difficult. In this case, if one element fails, the entire relay block may need to be replaced.
In Z51 models (since 2008), the system has become more modular. The relays are located in different blocks, which makes it easier to find the faulty element. However, the logic of operation has become more complicated: turning on the compressor now depends not only on the freon pressure, but also on the temperature of the evaporator and the load on the engine.
Particular attention should be paid to the wiring leading to the relay. On cars with high mileage, the insulation of wires in the engine compartment may crack due to vibration and temperature changes. This leads to short circuits that burn not only the relay, but also the tracks on the fuse block board.
When replacing the relay with Murano Z51 is also worth checking the condition of the connectors. Oxidation of the contacts in the connector can simulate a malfunction of the relay itself. Use dielectric grease during assembly to prevent future corrosion. This is especially true for cars operated in conditions of high humidity or reagents.
Hidden problem with mass
Often the problem of lack of cold does not lie in the relay, but in poor ground contact of the compressor itself or the pressure sensor. Check the condition of the ground bolts on the engine and body. The oxidized mass can give false signals, due to which the ECU blocks the supply of voltage to the relay, even if it is working properly.
Prevention and service life extension
In order for the air conditioner relay to serve for a long time, you must follow simple operating and maintenance rules. Regularly checking the air conditioning system for leaks and freon levels indirectly affects the operation of the relay. If there is little freon in the system, the compressor will work with increased load or turn on/off too often, which accelerates wear on the relay contacts.
Keep the radiators of the cooling system clean. A radiator clogged with dust and lint leads to overheating of the system, which forces the fans to work at their limit. Constant operation at high currents causes heating of the relay and fuse box, reducing their life.
It is recommended to carry out a visual inspection of the fuse and relay box every 2-3 years, especially if the car is operated in harsh climatic conditions. If you find traces of oxidation or darkening of the plastic, take immediate action: clean the contacts, replace the damaged element.
Do not leave the air conditioner on with the engine off for a long time. Although modern systems are protected, this places unnecessary stress on the battery and relays, which can lead to their failure in the long run. Always turn it off A/C before stopping the engine.
Regular cleaning of radiators and monitoring the freon level is the best prevention of overloading of the air conditioner relay, allowing you to avoid expensive electrical repairs.
Why does the air conditioner work and then stop after 10 minutes?
This may be due to overheating of the relay or pressure sensor. If a relay overheats, its internal contacts may lose contact due to thermal expansion. This may also indicate a clogged system or a malfunction of the pressure sensor, which turns off the compressor when critical values are reached.
Is it possible to replace the air conditioner relay yourself if you have no experience?
Yes, replacing a relay is one of the simplest operations in car repair. You don't need to disassemble the engine or remove complex components. All you have to do is find the fuse box, remove the old relay and insert the new one. The main thing is to make sure that you are removing the air conditioning relay and not the fan or fuel pump.
What should I do if the new relay burns out immediately after installation?
If the new relay fails instantly, it is a sign of a serious problem in the circuit: a short circuit in the wiring to the compressor, a seized compressor, or a problem with the control unit. In this case, you must immediately stop operating and contact an auto electrician for in-depth diagnostics.
How to distinguish a fan relay from a compressor relay visually?
They usually have the same shape and size, but differ in markings on the body or color. The relay body is often marked with a contact diagram or name (COMP for compressor, FAN for fan). They can also be located in different sockets of the fuse box, as indicated in the diagram on the cover.
Does the quality of freon affect the operation of the relay?
Indirectly affects. If there is a lot of moisture in the system or low-quality freon, this can lead to ice formation on the sensors or corrosion of contacts inside the system. This causes nuisance trips or overloads, which can shorten the life of relays and other electrical components.