2009 Mercedes-Benz ML320 Air Conditioning Refrigerant Line Replacement Cost

The air conditioning refrigerant lines should last the lifetime of the vehicle. However, it is not uncommon for the o-ring seals at the connecting ends of a line to deteriorate over time and cause refrigerant to leak out. It is possible for the refrigerant lines to become damaged if the vehicle is in a crash, or during careless service of other components in the engine compartment.

By using specialized equipment, a technician may place a vacuum on the air conditioning system to determine if the system is leaking. If a leak is present, the technician can gently pressurize the system and employ one or more techniques to determine the location of the leak. Oil that is present in the refrigerant under normal circumstances may be present at a leak site. The oil may be especially noticeable if the leak is on the condenser. A soap and water mixture can help locate where refrigerant is escaping from a line or connection. A dye can be injected into the system. This dye shows up under black light and can sometimes be seen escaping from a leak site. Finally, a tool called a leak detector can be used to "sniff" out leaking refrigerant.

Once a damaged or leaking air conditioning refrigerant line has been located, a technician will use specialized equipment to evacuate any remaining refrigerant in the air conditioning system. Any engine accessories or components that are in the way will need to be removed before the line is disconnected, removed, and replaced. It will also be necessary for the technician to determine how much refrigerant needs to be installed in the system after the refrigerant line has been installed.

RepairPal recommends that the air conditioner be operated at least once a month to ensure that the refrigerant and oil in the system is circulated regularly. It should be noted that a puddle of water forming under the vehicle is a natural byproduct of condensation when the air conditioner is running. If a refrigerant line is found to be damaged (bent or crushed) but not leaking, it is recommended that the line be replaced as soon as possible to prevent restriction of the flow of refrigerant and premature AC compressor failure.

Because it is illegal to vent refrigerant into the atmosphere, and because the Environmental Protection agency requires that a technician be certified to recover refrigerants, it is advised that service of the air conditioning system be left to a professional. In addition, a technician must understand how much refrigerant to add at a given air temperature to prevent the common DIY repair problem of overcharging the system with too much refrigerant. This places a burden on the system that can cause premature failure. The correct type of refrigerant must be used and the proper equipment to evacuate, reclaim, and recharge the air conditioning system is necessary.