Replacing the heater on a Nissan Sunny: detailed instructions with nuances for B14 and B15

Replacing the heater radiator with Nissan Sunny (especially models B14 And B15) is a task that every owner faces sooner or later. Over time, antifreeze corrodes the aluminum honeycombs, leaks appear, and there is a persistent smell of antifreeze in the cabin. The service will charge from 8 to 15 thousand rubles for such work, but if you have the tools and patience, you can do it yourself - the main thing is to know the pitfalls.

In this article you will find step-by-step instructions with photos, a list of necessary tools, connection diagrams for pipes and tips on how to avoid mistakes. We will look at the features of replacement on models with and without air conditioning, and also tell you how to check the performance of the system after repair. If your heater blows cold air or there is a puddle of antifreeze under the passenger’s feet, these instructions are for you.

Signs of a malfunctioning heater radiator on a Nissan Sunny

First call - reduction in interior heating efficiency. If at maximum fan speed the air is barely warm and the engine temperature is normal, the problem is most likely in the heater. But there are other symptoms:

• 💧 Antifreeze puddles under the front passenger floor mat (the fluid is usually sticky and has a sweet smell).
• 🌫️ Fogging of windows from the inside, even in dry weather - a sign of evaporation of antifreeze in the cabin.
• 🔥 Engine overheating during long-term operation - if the heater radiator is clogged, the circulation of antifreeze is disrupted.
• 🚗 Whistling or gurgling from under the dashboard when the heater is turned on (air lock or leak).

On Nissan Sunny B15 with air conditioning, another feature is added: condensation on driver's side floor. This is due to the fact that the air conditioner evaporator is located next to the heater radiator, and antifreeze can fall on it and then flow down.

⚠️ Attention: If antifreeze gets on the carpet, it needs to be delete urgently — antifreeze corrodes the polyurethane foam base of carpets and over time leads to corrosion of the body. Use moisture-absorbing granules (for example, for cat litter) and ventilate the interior for at least a day.

For an accurate diagnosis, check the antifreeze level in the expansion tank. If it falls without visible external leaks, and it’s dry under the car, the problem is definitely in the stove. On Sunny B14 (1995–2000) heater radiators fail more often due to thinner aluminum honeycombs.

Preparing for replacement: tools and spare parts

Before removing the torpedo, make sure you have everything you need. Main tool:

• 🔧 Set of sockets and ratchets (required) 10 mm, 12 mm, 14 mm).
• 🔨 Screwdrivers: Phillips (PH2), flat, short cross for hard-to-reach places.
• 🗝️ Pliers and round nose pliers for clamps.
• 🔪 Knife or scalpel for cutting pipes (if they are stuck).
• 🧲 Telescopic magnet - will save fallen bolts in the depths of the torpedo.

Spare parts and consumables:

Name	Article (original/analogue)	Note
Heater radiator	27210-4M000 (original) KR210114 (Koyorad)	For B14/B15 without air conditioning. With air conditioning - 27210-4M001.
Stove pipes	27240-4M000 (top) 27241-4M000 (lower)	It is better to replace them as a set - the old ones become tan and crack.
Clamps	16510-4M000 (original) or standard clamps 16–22 mm	Minimum 4 pieces (preferably 6 - in reserve).
Antifreeze	Nissan L250 (green) or CoolStream A-110	The system volume is 6.5 liters, but 4 liters is enough for replacement.

If you have Nissan Sunny with air conditioning, you will additionally need:

• 🔄 O-rings for air conditioner pipes (27275-4M000).
• 🧊 Vacuum pump for refilling freon (if you have to depressurize the system).

Important: When purchasing a radiator, pay attention to direction of pipes — on B14 and B15 they are different! On B14 the upper pipe is bent at an angle, on B15 it is straight. Also check the package: the box should contain rubber seals for attaching the radiator to the stove body.

Removing the torpedo: step-by-step instructions with photos

The most time-consuming step is dismantling the instrument panel. On Nissan Sunny the torpedo can be removed partially (center console only) or completely. We recommend the second option - it’s more convenient to work, especially if you’re doing this for the first time.

Procedure:

1. Disconnect the battery (remove the negative terminal).
2. Remove steering wheel (unscrew the nut on 19 mm and disconnect the airbag connectors).
3. Dismantle plastic linings around the steering column (2 screws PH2 and 2 latches).
4. Unscrew torpedo mounting bolts:
   • 2 bolts under the steering wheel (10 mm);
   • 2 bolts on the sides of the center console (12 mm);
   • 4 bolts on top (under the decorative trim of the windshield).

Disconnect all connectors (photo below) and carefully pull the torpedo towards you.

Take a photo of the location of the connectors|Mark bolts of different sizes with a marker|Place cardboard under the dashboard to avoid scratches|Prepare a box for small items (bolts, clips)|Disconnect the battery-->

On models with air conditioning you will need additionally:

• 🔧 Disconnect the air conditioner pipes (previously release freon!).
• 🔌 Remove the climate control unit (unscrew 4 screws PH1 and unfasten the connector).

⚠️ Attention: On Sunny B15 with air conditioning available additional bolt The torpedo mounts under the glove compartment are easy to miss! If the panel does not move, check this area.

After removing the torpedo you will have access to the stove body. On Nissan Sunny it is secured with 4 bolts (10 mm) and two plastic latches. Carefully remove the housing so as not to damage the dampers.

Removing the old radiator and installing a new one

When the heater body is removed, you will see a radiator with two pipes. Don't rush to cut them off - first try loosening the clamps. If the pipes are stuck (which happens in 90% of cases), proceed as follows:

1. Using a knife, carefully cut the pipe lengthwise without touching the radiator.
2. Rotate it around the axle to loosen the clutch.
3. Remove the clamps and take out the radiator.

Installing a new radiator:

• 🔧 Check it out direction of pipes — the top one should be on the engine side, the bottom one on the passenger compartment side.
• 🛠️ Place new rubber seals on the radiator (included).
• 🔄 Connect the pipes after lubricating them sealant for cooling system (For example, ABRO 11-AB).
• 🔩 Tighten the clamps evenlyso as not to pinch the pipes.

Critical point: on a Nissan Sunny B15 with air conditioning, the heater radiator has an additional plastic guide groove at the bottom. If it is not inserted into the groove of the housing, the radiator will dangle and the pipes will quickly leak!

After installing the radiator, reassemble the heater body in the reverse order. Before installing the torpedo, check the operation of the valves manually - they should move smoothly, without jamming.

Flushing the cooling system and refilling with antifreeze

If you don't flush the system, remnants of old antifreeze and rust the new radiator will quickly clog up. On Nissan Sunny Washing is done in 3 stages:

1. Pre-rinse with water:
   • Pour distilled water into the system.
   • Start the engine and let it idle for 10 minutes.
   • Drain the water through the faucet on the radiator.
2. Cleaning with special means (For example, LAVR Radiator Flush Classic):
   • Dilute the product in water according to the instructions.
   • Pour into the system and let it run for 30 minutes.
   • Drain and rinse with water 2 more times.
3. Refilling with antifreeze:
   • Close the heater tap (lever in the cabin to the “cold” position).
   • Fill antifreeze through the expansion tank to the mark MAX.
   • Start the engine, warm up to operating temperature.
   • Add antifreeze to the level (the system will “expel” air).

Error	Consequences	How to avoid
The system was not flushed	The honeycomb of the new radiator is clogged, the stove does not heat	Use cleaning agent and distilled water
Added antifreeze with air	Air lock → engine overheating	Warm up the engine with the reservoir cap open
Tightened the clamps	Cracks in pipes, leaks	Tighten with a force of 1.5–2 Nm

On Sunny B14 after refilling antifreeze be sure to check the operation of the thermostat. If the lower radiator hose remains cold when the engine is warm, the thermostat is stuck and needs to be replaced (21200-4M000).

Functionality check and typical problems after replacement

After assembly, start the engine and check:

• 🔥 Air temperature from the stove - at maximum airflow there should be at least 60–70°C.
• 💧 No leaks under the car and in the cabin (especially under the passenger’s feet).
• 📉 Antifreeze level — it should not fall after warming up.
• 🚗 Damper operation (switch the blowing modes - the air should blow from the desired deflectors).

Typical problems after replacement:

• 🌬️ The stove blows cold air - air lock. Solution: Stop the engine, let it cool, remove the upper radiator hose and add antifreeze.
• 🔊 Whistle or noise when the fan is running, the heater motor bearing is faulty (27300-4M000).
• 💦 Condensation in the cabin — The radiator or pipes are leaking. Check clamps and seals.

What to do if after replacing the stove heats poorly?

1. Check thermostat - if it opens too early, the antifreeze does not have time to warm up.

2. Make sure that stove faucet opens completely (on B15 it is electric, check the connector).

3. Inspect flaps - they could have moved during assembly.

4. If the problem persists, perhaps engine cooling radiator clogged - wash it separately.

On Nissan Sunny with air conditioning after replacing the stove it may climate control stops working. This is due to the fact that when removing the dashboard, the control unit connector is disconnected. Solution: Reset by disconnecting the battery for 10 minutes.

Cost of service work vs independent replacement

Prices for replacing a stove radiator in services vary depending on the region and complexity of the work:

Service	Cost (₽)	Time (hours)
Replacing the heater radiator (without air conditioning)	8 000 – 12 000	4–6
Replacing the heater radiator (with air conditioning)	12 000 – 18 000	6–8
Flushing the cooling system	1 500 – 3 000	1–2
Refilling antifreeze	500 – 1 000	0.5

Self-replacement will cost:

• 🔧 Heater radiator: 2 500 – 4 000 ₽ (original/analogue).
• 🛢️ Antifreeze: 1 000 – 1 500 ₽ (4 l).
• 🔩 Pipes and clamps: 800 – 1 200 ₽.
• 🧼Rinsing: 300 – 500 ₽.

If you are not confident in your abilities, you can save on spare parts: buy a radiator and antifreeze yourself, and only pay for the work at the service center. Many service stations make concessions if the client brings his own parts.

FAQ: Frequently asked questions about replacing the heater on a Nissan Sunny

Is it possible to replace the heater radiator without removing the dashboard?

On Nissan Sunny B14/B15 partial dismantling possible, but extremely inconvenient. Only the center console and glove compartment can be removed, but access to the radiator will be limited. The risk of damaging pipes or dampers increases 3 times. If this is your first time doing this, it is better to remove the torpedo completely.

What antifreeze is best to fill in after replacement?

The best option is original Nissan L250 (green) or its analogues:

• CoolStream A-110 (red, compatible with aluminum radiators);
• Sintec Unlimited (purple, service life up to 5 years);
• Felix Carbox G12+ (red, does not require dilution).

Do not mix antifreeze of different colors! If you don’t know what was previously filled, flush the system and use any of the above.

Why, after replacement, does the stove heat only while running?

This is a sign insufficient antifreeze circulation at idle speed. Reasons:

1. There is an air lock in the system (needs bleeding).
2. Defective coolant pump (pump). On Sunny B15 its resource is 100,000 km.
3. clogged main cooling radiator (rinse or replace).

Check also thermostat - if it opens too early, the antifreeze does not have time to heat up.

How long does a heater radiator last on a Nissan Sunny?

The service life depends on the quality of the antifreeze and operating conditions:

• Original radiator (Nissan) — 8–10 years or 150,000 km.
• Analogs (Koyorad, Denso) — 5–7 years or 100,000 km.
• Cheap Chinese radiators — 2–3 years (often leaking at the seams).

How to extend the life of a radiator?

• Change antifreeze every 60,000 km or once every 3 years.
• Use only silicate-free antifreezes (silicates corrode aluminum).
• Flush the system periodically distilled water.

Is it possible to drive with a faulty heater?

Short term - yes, but with reservations:

• If the stove does not heat, but antifreeze does not go away — you can drive, but in winter it’s uncomfortable.
• If there is antifreeze leak — You can't drive! Risk of engine overheating and cylinder head seizure.
• If antifreeze gets into the cabin - dangerous to health (toxic fumes).

On Nissan Sunny B14/B15 with a faulty stove the load on the cooling system increases, since antifreeze circulates only in a small circle. This can lead to overheating in summer.