Is the thicker or thinner car AC pipe the high-pressure one?
4 Answers
The thinner one is the high-pressure intake pipe, while the thicker one is the low-pressure pipe. Additionally, there are other methods to distinguish between high and low-pressure intake pipes: 1. By path: The low-pressure pipe runs from the evaporator to the compressor, while the high-pressure pipe runs from the compressor to the condenser, then from the condenser to the evaporator. 2. By letters near the compressor connection: Some compressors have letters like S or D marked near the connections to differentiate, where S stands for the low-pressure connection and D for the high-pressure connection. 3. By temperature: Start the car and turn on the AC, then feel the pipes with your hand—the cooler one is the low-pressure pipe, and the hotter one is the high-pressure pipe.
To be honest, I remember the car air conditioning pipes quite clearly, as I've been dealing with them for over a decade. In a car's air conditioning system, the thicker pipe is generally the low-pressure line, while the thinner one is the high-pressure line. This is mainly because the refrigerant coming from the compressor is under high pressure but has a small volume, so a thin pipe is sufficient—using a thicker one would cause waste and over-compression. On the other hand, the refrigerant returning from the evaporator has low pressure but a large flow rate, requiring a thicker pipe to move smoothly. From my experience repairing many cars, I've found that mixing up the pipe sizes can lead to system overheating or even bursting, which is a real headache. My advice is to check the thick pipe connected to the evaporator during routine inspections—it usually feels cool to the touch, while the thin pipe connected to the compressor may feel warmer. Knowing this distinction can save you a lot of hassle during maintenance and prevent damage to the air conditioning system.
I find this topic quite interesting, as I love tinkering with cars and often do disassembly and assembly work myself. In car air conditioning systems, the thicker pipe is the low-pressure line, while the thinner one is the high-pressure line. It's actually quite straightforward: the compressor pushes high-pressure gas to the condenser, and since the gas is highly compressed, a thinner pipe suffices. On the other hand, the returning low-pressure gas has a larger volume, so a thicker pipe is needed for smooth flow. When I DIY my AC repairs, I've used pressure gauges to confirm this—the readings on the thicker pipe are always lower. If you accidentally connect them wrong, the valves might get clogged or leak refrigerant. Now, when I maintain my car, I pay attention to the pipe positions: the thick pipe is usually connected near the evaporator, while the thin one is more visible in the engine bay. This knowledge is really practical, especially in summer when AC repairs become more frequent.
I've been driving for years and know a thing or two about car air conditioning. Simply put, the thicker pipe in a car's AC system is the low-pressure line, while the thinner one is the high-pressure line. The principle is quite straightforward: high-pressure gas is compressed and dense, so it doesn't take up much space, and the thin pipe can handle it. Low-pressure gas, on the other hand, has a large flow rate and is loose, so a thick pipe is needed to avoid blockage. Just remember that the thick pipe connects to the evaporator side. This question reminds me that during AC maintenance, if the pipes are connected incorrectly, the compressor might hum or the cooling performance could be poor. It's best not to tamper with the pipes to avoid trouble, and it's safer to have a professional check them promptly.
