What is the intermittent hissing sound from the car air conditioner?

1 Answers
DelChase
07/30/25 9:01am
Car air conditioner intermittent hissing sound is the noise of refrigerant flowing in the radiator. Here is the relevant introduction about car air conditioner refrigerant: 1. Working principle: When the air conditioner is operating in cooling mode, the low-temperature and low-pressure refrigerant gas is compressed by the compressor into high-temperature and high-pressure refrigerant gas. The high-temperature and high-pressure refrigerant gas releases heat in the condenser (generally air-cooled, i.e., the heat dissipation copper pipe of the outdoor unit) and turns into medium-temperature and high-pressure liquid (the heat is carried away by the outdoor circulating air). The medium-temperature and high-pressure liquid then passes through the capillary tube to expand and reduce pressure, becoming low-temperature and low-pressure liquid. The low-temperature and low-pressure liquid refrigerant absorbs heat in the evaporator (indoor unit copper pipe) and evaporates into low-temperature and low-pressure gas (indoor air is cooled by passing through the heat exchanger surface). 2. Refrigerant charging method: Under normal temperature and pressure, R410A is a chlorine-free fluorinated alkane non-azeotropic mixed refrigerant, appearing as colorless gas stored in steel cylinders. Based on the characteristics of R410a, an application practice was conducted to replace HCFC22 with R410a in a room air conditioning system, including theoretical analysis and system matching. Experimental results show that under the same conditions, compared with HCFC22, the heat transfer coefficient increases, flow resistance decreases, and after system optimization matching design, the performance (COP) is significantly improved, reaching the European market Class A energy efficiency level.
Was this review help?
13
1
Share
More Forum Discussions

How Many Liters of Transmission Fluid Does the Kia Sportage Need?

The Kia Sportage requires 6 to 7 liters of transmission fluid for a change. Below are the relevant details: 1. Powertrain: The Kia Sportage offers a 2.0L or 2.4L engine, with maximum output power of 165 horsepower and 174 horsepower respectively. The transmission is paired with either a 6-speed manual or a 6-speed automatic transmission. 2. Exterior Design: The front grille of the Kia Sportage abandons the four-slat design of the current model in favor of a five-slat design. The size of the front grille has also been reduced, allowing the bottom line of the grille to align seamlessly with the bottom line of the headlights. Additionally, the Kia logo, which was positioned in the middle of the front grille in the older model, has been relocated to the engine hood in the new model. These changes enhance the overall cohesive appearance of the front fascia of the new Kia Sportage.
14
1
Share

What are the reasons for difficulty in engaging first gear in Jetta?

Jetta difficulty in engaging first gear may be caused by the following reasons: 1. Loose or severely worn shift fork, or even deformation: Loose screws fixing the shift fork can result in incomplete gear engagement. When the shift fork is severely worn, it cannot move the gear, causing difficulty in shifting. In this case, the damaged shift fork should be repaired or replaced, and the fixing screws should be tightened. 2. Wear of the positioning groove and positioning pin: The surface becomes irregular, sometimes jamming during gear shifting, preventing the positioning pin from sliding out of the groove, resulting in difficulty in engaging gears or shifting. This should be repaired. 3. Deformation of the shift shaft: This makes it difficult for the sliding gear to move. In this case, the shift shaft should be repaired or replaced. 4. Incomplete clutch disengagement: Even slipping may occur, causing the gears in the transmission to continue rotating during shifting, making it difficult to shift. In this case, the clutch should be adjusted.
11
2
Share

What is the maximum speed when visibility is 50 meters in rain or snow?

When visibility is less than 50 meters on highways during rain or snow, the maximum speed should be 20 km/h, and drivers should exit the highway at the nearest exit as soon as possible. According to the "Regulations for the Implementation of the Road Traffic Safety Law," when encountering heavy rain, snow, or fog with visibility less than 200 meters, drivers should turn on fog lights, low beams, marker lights, and front and rear position lights. The speed should not exceed 60 km/h, and a distance of more than 100 meters should be maintained from the vehicle ahead in the same lane. When visibility is less than 100 meters, in addition to fog lights, low beams, marker lights, front and rear tail lights, and hazard warning flashers (double flashers) should also be turned on, and the speed should not exceed 40 km/h. When visibility is less than 50 meters, the safest approach is to avoid driving if possible. Drivers should turn on all available lights, such as fog lights, low beams, marker lights, front and rear position lights, and hazard warning flashers, but must avoid using high beams. Additionally, drivers should ensure the vehicle speed remains below 20 km/h and use the horn appropriately when unsure about the presence of vehicles or pedestrians ahead or behind, serving as a warning.
6
4
Share

What does the HAC hill-start assist system mean?

Hill-start Assist Control (HAC) is a function derived from the ESP system. It allows the vehicle to maintain braking for a few seconds after the driver's right foot leaves the brake pedal when starting on a slope without using the handbrake. This enables the driver to easily move their foot from the brake pedal to the accelerator pedal, preventing rollback accidents and avoiding panic situations. Additional information: 1. Conditions for hill-start assist system activation: The gearshift lever is in any position other than P (for automatic transmission models); the accelerator pedal is not depressed; the vehicle is stationary; the parking brake (handbrake or foot brake) is not engaged. 2. Principle of HAC: When starting on a slope, the moment the driver's foot leaves the brake pedal to press the accelerator, the HAC system automatically maintains brake hydraulic pressure for 2-3 seconds, equivalent to the brake still being pressed, so the vehicle won't roll back. When the accelerator is pressed, HAC's brake control automatically ends, and it doesn't release all braking force at once but gradually reduces it, allowing the vehicle to start smoothly with the accelerator. If the accelerator isn't pressed, HAC's automatic brake control will also end after 2-3 seconds, so the driver can press the accelerator at a relaxed pace.
16
1
Share

8th Generation Accord: Should I Use 92 or 95 Octane Gasoline?

The 8th generation Accord can use 92 octane gasoline. This octane rating is officially recommended in the vehicle's user manual. In addition to checking the appropriate gasoline octane in the user manual, the recommended octane rating is also indicated on the fuel tank cap. You can usually determine the suitable gasoline grade based on the engine's compression ratio. Vehicles with an engine compression ratio between 8.6-9.9 should use 92 octane gasoline, while those with a compression ratio between 10.0-11.5 should use 95 octane. If the compression ratio is even higher, 98 octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the required gasoline grade. Engines with high compression ratios can also be tuned to use lower-octane gasoline due to factors such as ignition timing, turbocharging technology, and Atkinson cycle technology. Generally, the higher the gasoline octane rating, the higher the octane number and the better the anti-knock performance. 92 octane gasoline contains 92% isooctane and 8% n-heptane, while 95 octane gasoline contains 95% isooctane and 5% n-heptane. If you occasionally use the wrong gasoline octane in the 8th generation Accord, simply switch back to the correct octane after consumption. However, prolonged use of the wrong octane may have the following effects: For vehicles designed for lower octane, using higher-octane gasoline will not cause damage, but the increased octane number may alter the fuel's ignition point, leading to delayed combustion in the engine. This reduces the engine's power output and thermal efficiency, resulting in poorer performance. For vehicles designed for higher octane, using lower-octane gasoline may cause engine knocking. Since the octane number is significantly lower, the fuel may ignite prematurely during the compression stroke before the spark plug fires. This premature ignition creates resistance during the upward stroke, causing unstable engine operation. Mild knocking may only increase noise without noticeable engine damage, but severe knocking indicates serious engine issues, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring.
3
3
Share

Is the Traverse engine domestically produced or imported?

The engine used in the Traverse is domestically produced. For Chevrolet, except for the engines of imported vehicles like the Camaro, Colorado, and Silverado which are manufactured in the United States, the engines for other models are produced in China. The engine model used in the Traverse is the LXH, with a maximum horsepower of 237 HP, a maximum power of 174 KW, a maximum power speed of 5400-5700 rpm, and a maximum torque of 350 Nm. For daily maintenance of the Traverse engine, the following methods can be used: Use lubricating oil of appropriate quality grade. For gasoline engines, select SD--SF grade gasoline engine oil based on the additional devices of the intake and exhaust systems and usage conditions; for diesel engines, choose CB--CD grade diesel engine oil according to the mechanical load, with the selection standard not lower than the manufacturer's specified requirements; Regularly change the oil and filter. The quality of any grade of lubricating oil will change during use. After a certain mileage, the performance deteriorates, which can cause various problems for the engine. To avoid malfunctions, change the oil regularly according to usage conditions and maintain an appropriate oil level; When oil passes through the fine pores of the filter, solid particles and viscous substances in the oil accumulate in the filter. If the filter is blocked and oil cannot pass through the filter element, it may burst the filter element or open the safety valve, allowing oil to bypass and carry contaminants back to the lubrication area, accelerating engine wear and increasing internal contamination; Regularly clean the crankcase. During engine operation, high-pressure unburned gases, acids, moisture, sulfur, and nitrogen oxides from the combustion chamber enter the crankcase through the gap between the piston rings and cylinder walls, mixing with metal powder from component wear to form sludge. A small amount remains suspended in the oil, while a large amount precipitates, clogging filters and oil passages, making engine lubrication difficult and causing wear; Regularly use a radiator cleaner to clean the radiator. Removing rust and scale not only ensures the engine operates normally but also extends the overall lifespan of the radiator and engine.
3
0
Share
Cookie
Cookie Settings
© 2025 Servanan International Pte. Ltd.