The A/C suction hose pipe is the low-side line. It carries cold refrigerant gas from the cabin back to the compressor. Because it handles cold gas, this hose is larger in diameter than the high-side lines and feels cold and wet to the touch when the system is running.
Mechanic Glossary
A/C Suction Hose Pipe
The low-pressure line that carries cold, vaporized refrigerant from the evaporator outlet back to the compressor inlet.
Frequently Asked Questions
The thicker metal line in the engine bay. It has the low-side service port labeled with an 'L' and is cold to the touch.
Frost indicates that the evaporator is freezing. This is usually caused by low refrigerant levels, a clogged cabin filter, or a bad temp sensor.
Yes. Since this line runs under low pressure, a leak can draw air and moisture into the system, which degrades cooling performance.