With the onset of cold weather or in the hot summer heat, each driver strives to create the most comfortable conditions in the cabin. One of the key systems responsible for the microclimate is climate control or a simple “oven”, in the arsenal of which there is a button with the image of the car and an arrow inside. Many people ignore this function, relying solely on air intake from the street, but understanding the principle of operation. recycling It allows you to solve complex problems of cleaning the cabin and rapid temperature change.
In fact, this mode blocks the access of external air through the air intake, forcing the system to drive the volumes already inside through the cabin filter and heat exchanger. This creates a closed loop that has its own undeniable benefits, but also carries hidden threats to the health of the driver if used incorrectly. In this article, we will examine the physics of the process in detail, look at common mistakes and find out when the Recirc button becomes your best friend and when it can cause serious problems.
It is important to note that modern climate management systems such as Climatronic from Volkswagen or Dual Zone Toyota can automatically control the valves depending on the air quality, but knowledge of manual mode is necessary for every driver to control the situation.
Principle of operation of the system and main differences
In standard operating mode, a heating, ventilation and air conditioning (HVAC) fan draws air from outside the vehicle. Usually, the air intake is located at the base of the windshield, where the air pressure during movement is maximum. Passing through cabin filterThe stream is cleaned of large dust, leaves and insects, and then sent to the air conditioner evaporator or heat heat heat heat treatment.
When you activate the recycling mode, a special flap (often electric drive) covers the outside air intake channel. At this point, the system begins to work exclusively with the internal volume of the cabin. Air is forcibly sucked through special holes, often located in the lower part of the torpedo or in the leg area, undergoes cleaning and temperature preparation, and then returns to the cabin through deflectors.
The main difference is the speed of processing the air mass. Since the system does not need to waste energy heating or cooling fresh streams from the street, which can have extreme temperatures, the change in parameters is much faster.
Technical details of the work of the valve
The recirculation valve can have a cable drive (in older cars) or an electric servo drive. In modern systems, it is often combined with an air quality sensor that automatically blocks access when carbon monoxide or exhaust gases are detected.
It is important to understand that in a closed cycle mode air-conditioner It works with a lower load on the compressor, since it does not need to constantly cool the hot outdoor air, but only maintain the temperature of the already cooled internal volume.
When to Include Recycling Regime
There are a number of situations when the use of a closed loop is not just a convenience, but a necessity. First of all, this concerns traffic in dense urban traffic or standing in traffic jams, when trucks, buses and old cars in front of you actively emit combustion products into the atmosphere.
In such conditions, turning on recycling protects you and passengers from inhalation. carbon monoxide (CO) and other toxic compounds, the concentration of which in the exhaust gases can be fatal if prolonged exposure in a confined space. This mode is also indispensable for passage through tunnels, where ventilation is often absent, and the concentration of exhaust gases reaches peak values.
Another scenario is the need for extremely rapid cooling of the cabin in the heat or, conversely, its warming up. If you leave your car in the sun, the temperature inside can reach 50-60 degrees Celsius. Turning on the recycling mode together with the air conditioner allows you to reduce the temperature to comfortable many times faster than when taking hot air from the street.
☑️ Pre-introducement checks
However, it is worth remembering that this mode is not designed for continuous operation for a long time, as it does not enrich the air with oxygen.
Protection from odors and harmful impurities
One of the most obvious features of the recycling button is protection against unpleasant odors. Imagine the situation: ahead is a garbage truck, a dump truck with dusty cargo or just a diesel truck sneezing from old age, wrapping everything around in black smoke. At this point, the instant switch to the internal cycle allows you to isolate the cabin from the aggressive external environment.
In addition, this regime is effective when driving through industrial areas where chemical fumes may be present in the air, or farmland during pesticide treatment. Even if you cabin filter With a carbon layer that traps odors well, complete isolation from the source of contamination is a more reliable method of protection.
Keep in mind that not all smells disappear instantly. If the unpleasant aroma has already penetrated the cabin, for example, from a passing cattle truck, then the inclusion of recycling will prevent the receipt of a new portion, but it will take time and high-quality filtration to clean the existing volume.
If you smell a sharp chemical odor or smoke, turn on recycling immediately, but try to also cover the windows if they have been ajar to create maximum leakage.
Owners of cars with diesel engines should be especially careful, as modern particulate filters (particulate matter filters)DPF) a specific odor may be emitted during regeneration mode, which is better not to be inhaled.
Effects on glass fogging and humidity
This is one of the most common myths and mistakes drivers make. It is believed that recycling always helps to fight fogging. This is true only in one case: if you dry air conditioning in rainy weather, but apply it to the windshield. However, the recycling regimen is often cause fogging.
It's physics: the air exhaled by man contains a huge amount of moisture. In the enclosed space of the cabin, humidity grows rapidly. When this moist air hits the cold glass, condensation occurs, and visibility drops sharply. Therefore, in winter, using the recycling mode unnecessarily is a direct path to the fog inside the car.
To effectively remove moisture, it is necessary to use fresh air from the street, since winter air, even at high relative humidity, contains less absolute water vapor than warm air in the cabin. Warming up dry outdoor air, we get an effective means for draining glass.
| Situation | Air intake mode | Air conditioning (A/C) | Temperature. |
|---|---|---|---|
| Dense traffic, exhaust gases | Recycling | Off/Auto | Comfort. |
| The glass is foggy (winter) | Street. | On | Warmth. |
| Quick salon warm-up | Recycling | Off | Max. heat |
| Fast cooling (summer) | Recycling | On | Min. coldness |
Modern climate control systems often have a logic that forcibly turns off recycling when windshield blowing mode is turned on to prevent fogging, but relying on automation is not always possible.
The dangers of prolonged use of the regime
The most important danger of using a recycling regime is a decrease in oxygen concentration and an increase in carbon dioxide (CO2) levels. A person at rest consumes oxygen and exhales CO2. In the airtight volume of a modern car, especially if there are several passengers in the cabin, carbon dioxide levels can rise to values that cause drowsiness, decreased concentration and headache.
Warning Block: ️ Attention! Long-term exposure to multiple passengers can cause the driver to lose consciousness due to hypoxia. Do not use this mode for more than 15-20 minutes in a row without short-term ventilation.
In addition, if the car has malfunctions associated with the entry of exhaust gases into the cabin (for example, a crack in the exhaust manifold or leaky exhaust system under the bottom), then the inclusion of recycling can be fatal, as it will draw these gases from the street through the looseness of the body and concentrate them inside.
It is also worth considering that in the closed cycle mode, the moisture released by breathing and wet clothes does not disappear anywhere. This can lead to an increase in humidity, which in winter is fraught with icing of the glass from the inside, and in summer - the appearance of mold in the ducts and on the air conditioner evaporator.
Regular air change is essential to keep the driver alert, so the 15 minute recycling rule is the gold standard for safety.
Features of work in winter and summer periods
In summer, recycling algorithms are the easiest and most efficient. As mentioned earlier, it allows you to cool the cabin faster. However, there is a caveat: if the car is very hot, the first couple of minutes it is better to drive with the windows open to throw out the hot air, and then turn on the recirculation with air conditioning to keep cool.
In winter, the situation is diametrically opposite. Many drivers include recycling to keep the cabin from blowing cold from the street. Indeed, the air temperature from the deflectors is getting higher faster. But as we have already found out, this is the path to fogging. The only safe way to use in winter is a short-term switch for quick warming up, with the obligatory subsequent switch to the fence from the street.
Modern systems such as Smart Climate ControlThey can adjust the valve by mixing a small amount of fresh air even in recycling mode to balance humidity and oxygen content, but in budget models this function is not.
In winter, use recycling only for short-term warming up, be sure to switch to outdoor air intake to combat fogging.
In the off-season, when it is damp and damp outside, recycling helps to avoid getting wet fog into the cabin, but again, requires monitoring the condition of the glasses.
Diagnostics of malfunctions of the recycling system
Like any mechanical assembly, the recycling valve control system can fail. Most often, the problems are associated with the electric drive of the valve or the cable mechanism. One of the first symptoms of malfunction is the appearance of a whistle or hum from under the torpedo when changing the ventilation modes.
If the flap jammed in the position “from the street”, then in the recycling mode you will still feel the smells from the road and the noise of the wind. If it is stuck in a closed position, the glass will sweat even with the blowing on, and the cabin will be constantly stuffy.
In some vehicles, for example, in the group models VAG or BMWIf the actuator of the flap fails, the indicator of the malfunction of the climate control can light up on the dashboard, and the corresponding code will remain in the error block.
⚠️ Warning: Attempting to forcefully open or close the jammed valve with your hands can lead to breakage of the plastic gears of the drive. Diagnostics and repairs require removal of part of the instrument panel.
To check the performance, you can conduct a simple test: on a silenced car, turn on the fan to the maximum and click the recycling button. A change in the sound of the fan motor (due to a change in airflow resistance) will indicate that the valve is moving.
How to check the work of the valve visually
In some cars (for example, Ford Focus 2) to the valve recycling can be approached by removing the glove compartment or part of the torpedo on the passenger side, and see the movement of the lever when you turn on the button.
FAQ: Frequently Asked Questions
Can I smoke in a car with recycling enabled?
It's not recommended. Salon filter is not intended to delay the combustion products of tobacco in such concentrations. You will quickly “clog” the filter, and the smell will infuse into the upholstery of the seats and the plastic torpedo, as the air will constantly circulate through the smoked volume.
Why does the noise from the fan become quieter in recycling mode?
It's normal. When the external air intake is closed, the resistance to the air flow changes, and the wind noise, which is drawn outside, disappears. The fan motor operates in a calmer aerodynamic environment.
Does recycling affect fuel consumption?
Indirectly, yes. When using air conditioning in recycling mode, the compressor works less intensively, since it cools already cold air, rather than hot street air. This reduces engine load and saves fuel, especially in the city.
What to do if the recycling button does not light up?
In some cars (such as older Mercedes or BMW models), the display may go out a few seconds after switching on, although the mode works. If the climate does not react, check the fuse of the HVAC system or the serviceability of the button itself.
Can I sleep in a car with recycling enabled?
It's deadly. In a closed space with a working engine (for the operation of the stove), the level of carbon monoxide can grow to critical values even with a serviceable exhaust system due to the gases sucking. To sleep in the car requires a constant supply of fresh air.