The engine cooling system is vital for any car, and the Nissan Almera is no exception. When the antifreeze temperature goes beyond acceptable limits, it is the radiator fan that must turn on to remove heat. In most cases, a compact but critical device is responsible for this process - cooling fan relay. If it fails, the engine can overheat even in cool weather, which will lead to serious consequences, including deformation of the cylinder head.
Owners Nissan Almera (both the new generation G15 and previous modifications) often encounter a problem when the fan runs constantly or, conversely, does not turn on at all. In 90% of cases, the culprit is not the fan motor itself, but the control relay or a control unit located in the mounting block. Understanding how this system works will help you quickly isolate the problem and avoid costly engine repairs.
Operating principle and location of the relay block
By car Nissan Almera The cooling fan is controlled through a special relay unit, which is located in the engine compartment. This unit receives signals from the electronic engine control unit (ECU) based on data from the coolant temperature sensor. When the antifreeze heats up to a certain threshold, the ECU closes the circuit, supplying power to the relay coil, which, in turn, turns on the fan itself.
The location of the block may differ slightly depending on the year of manufacture and engine model (for example, 1.6 L H4M or 1.5 L K4M). This is usually a black plastic unit mounted on the fender or next to the battery. There are several inside it relay and fuses. To access them, you need to remove the plastic cover, which is often marked with a diagram of the location of the elements, which greatly simplifies the search for the faulty component.
It is important to understand that modern cars often use more than one relay, but a complex circuit with several stages of fan rotation. This allows the system to operate in economy mode at moderate temperatures and at full power at extreme temperatures. Fan control unit may contain both classic electromagnetic relays and semiconductor switches, which are more resistant to voltage surges, but more difficult to diagnose.
Main symptoms of a relay malfunction
You can understand that something is wrong with the relay by indirect signs of the car’s behavior. The most obvious symptom is the fan not working when the temperature arrow reaches the red zone. In this case, you can hear a characteristic click from the relay block, but the fan itself will not start, which indicates sticking contacts or an open circuit inside the coil.
Another common scenario is that the fan runs continuously even after the engine has cooled down. This often happens because the relay contacts are stuck and will not open. In such a situation, the battery is quickly discharged, and the generator works with increased load. Sometimes there may be a burning smell from the engine compartment, which indicates melting of the housing relay due to overload.
It is also worth paying attention to the operation of the air conditioner. On Nissan Almera The cooling fan often turns on automatically when the climate control system is activated to cool the condenser. If the air conditioner is on but the fan is silent, this is a sure sign of a problem in the control circuit. Such symptoms cannot be ignored, since overheating can happen at any time, especially in traffic jams or when climbing a mountain.
⚠️ Attention: If the fan does not turn on and the temperature rises, stop immediately and turn off the engine. An attempt to get to the service center may lead to a major overhaul of the engine due to overheating.
Sometimes the problem lies not in the relay itself, but in the wiring or connectors. Corrosion of the contacts or oxidation at the connection points can simulate a relay failure. Therefore, before purchasing a new part, it is necessary to visually inspect the connectors for signs of melting or green deposits.
- The fan does not turn on
- The fan runs constantly
- The fan works intermittently
- No problem, I want to know in advance
Cooling system diagnostics
Before you change fan relay, it is necessary to conduct a thorough diagnosis to exclude other causes of failure. First of all, check the fuse responsible for the fan circuit. It is usually located in the same block as the relay and is marked to match the diagram on the cover. If the fuse is blown, replace it with one of equal amperage.
To check the relay itself, you can use the method of replacing a known-good element. Find a relay with the same markings in the block (for example, for headlights or headlights), carefully pull it out and insert it instead of the suspicious fan. If the fan starts working, the problem is in the relay. This method is the fastest and does not require special equipment.
A more accurate method is to use a multimeter. You need to check the resistance of the relay coil winding and the presence of continuity on the power contacts. If you don’t have a multimeter, you can try to “bridge” the power contacts of the relay with a screwdriver (taking precautions!). If after the short circuit the fan spins at normal speed, then the problem is definitely in the relay, and not in the fan motor itself.
⚠️ Attention: When bridging contacts, be extremely careful. You may receive an electric shock or cause a short circuit. Work only with the engine turned off and the battery terminal removed if you are not confident in your abilities.
How to test a relay without a multimeter?
Remove the relay and blow into the hole where the coil is located. If you hear a clear click, the mechanics are working properly. If not, the relay is “dead”. You can also shake the relay: if something rattles inside, it means there is a break inside and it needs to be replaced.
Don't forget to check the coolant temperature sensor as well. If it transmits incorrect data, the ECU simply will not give a command to turn on the relay, even if it is working properly. Errors in the temperature sensor are often recorded in the on-board computer's memory, which can be considered a scanner.
Relay and block replacement process
Replacing the relay with Nissan Almera - a procedure that any car owner with minimal skills can handle. You don't need a lift or complicated tools. It is enough to have a screwdriver to remove the relay box cover and perhaps pliers to pull out the old element if it is tight.
Before starting work, be sure to disconnect the negative terminal of the battery. This will protect the electronic components from accidental short circuits during manipulation. Open the hood, find the relay box, press the cover latches and remove it. Now you can see all the controls.
Pull out the faulty relay. Usually it is held in the block by plastic latches. Insert the new relay until you hear a characteristic click. Make sure it is level and all contacts are aligned. After this, return the cover to its place and connect the battery. Start the engine and warm it up to operating temperature to check the fan operation.
☑️ Check before launch
If the problem is not solved by replacing one relay, the control unit itself may be faulty. In some cases, the unit can be disassembled and the burnt elements can be re-soldered, but more often it is easier and more reliable to replace the entire unit. When purchasing a new unit, pay attention to the article number, as it may differ depending on the engine type and year of manufacture.
Replacing the relay is a cheap and quick procedure that can save the engine from overheating. Don't delay repairs at the first sign of trouble.
Selection of original and analogues
When choosing a spare part for Nissan Almera It’s worth thinking about: take an original relay or save on an analogue one. Original parts (OEM) guarantee perfect performance and long service life. However, their price can be significantly higher, especially if we are talking about a complex control unit.
Analogues from well-known brands such as Hella, Denso or Motorcraft, often offer excellent quality at a more affordable price. The main thing is to make sure that the relay parameters (operation current, voltage, number of contacts) completely match the original. An incorrectly selected relay may burn out on the first day of operation or may not cope with the load.
Avoid buying “no-name” parts from the markets, as their quality often leaves much to be desired. Internal contacts can be made of soft metals that quickly oxidize or melt. It’s better to overpay once for a trusted manufacturer than to change the relay every six months.
| Manufacturer | Originality | Approximate price | Service life |
|---|---|---|---|
| Nissan (OEM) | Original | High | 5+ years |
| Denso | High quality analogue | Average | 3-5 years |
| Hella | High quality analogue | Average | 3-5 years |
| Unknown brand | Cheap analogue | Low | 6-12 months |
Connection diagrams and pinouts
Understanding the wiring diagram will help you not only replace the relay, but also carry out more in-depth diagnostics. On Nissan Almera The fan relay usually has 4 or 5 contacts. 85 and 86 are the control coil contacts, 30 is the input power from the battery, 87 is the fan output, and 87a (if any) is a normally closed contact.
When checking the circuit, it is important to know that power is supplied to the relay constantly, and the control signal from the ECU grounds the coil. This means that if you test the control circuit, you will be looking for ground when triggered. Errors in the pinout can result in the fan running constantly or not turning on at all.
For an accurate diagnosis, it is recommended that you have the official electrical diagram for your model on hand. It is available in service documentation or specialized online databases. Never rely solely on intuition when working with electrical wiring.
Before removing the connector from the relay, be sure to photograph its location and the color of the wires. This will help avoid mistakes during reassembly if the contacts have oxidized and are difficult to distinguish visually.
Prevention and care of the system
To ensure that the fan relay lasts as long as possible, you must follow simple operating rules. Regularly clean the cooling radiator from dirt, fluff and leaves. A clogged radiator forces the fan to work at its limit, which increases the load on the relay and accelerates wear on the contacts.
Check the condition of the wiring in the engine compartment. High temperatures and vibrations can damage wire insulation over time, causing short circuits or poor connections. If you notice frays or cracks on the wires, immediately insulate them or replace the section of wiring.
It is also a good idea to periodically check the coolant level and condition. Using low-quality antifreeze can lead to corrosion inside the system, which also affects temperature sensors. Timely replacement of coolant will extend the life of the entire cooling system.
⚠️ Attention: Cleaning the radiator must be carried out carefully so as not to bend the aluminum honeycombs. Use a soft brush or compressed air, but do not clean the radiator with high pressure at close range.
Monitor the operation of the air conditioner. If you often turn it on in hot weather, make sure the fan responds adequately. Frequent on-off cycles can quickly wear out the mechanical parts of the relay, so any malfunctions in the climate system require immediate attention.
FAQ: Frequently asked questions from owners
Why does the fan run constantly after replacing the relay?
If, after replacing the relay, the fan continues to run without stopping, the problem may be stuck contacts inside the relay itself (if the new one is defective), a short circuit in the wiring between the relay and the computer, or a malfunction of the temperature sensor, which constantly signals overheating.
Is it possible to temporarily bridge the relay contacts in order to get to the service station?
Technically yes, but it's risky. If you bridge the power contacts, the fan will run constantly, which will drain the battery when the engine is off. This is only permissible for a short trip with the engine turned on and constant monitoring of the voltage level in the on-board network.
Where is the relay block located on Nissan Almera G15?
On the Nissan Almera G15, the relay and fuse box is usually located in the engine compartment, on the right side (passenger side) next to the battery. It is covered with a black plastic cover that needs to be snapped off to access the elements.
How much does a fan relay cost for a Nissan Almera?
The price of the original relay varies from 1,500 to 3,000 rubles, depending on the supplier. High-quality analogues are cheaper - in the range of 800–1500 rubles. A complete control unit can cost from 5,000 rubles and more.
What to do if the fan fuse is blown?
First replace the fuse with a new one of the same rating. If it burns out again after a short time, this indicates a short circuit in the circuit (in the fan motor itself or in the wiring). Do not install a fuse with a larger rating - this may cause a fire.