Three Reasons Your Old Mercedes AC May Not Be Running Efficiently

If you've owned your Mercedes car since the 1980s, you're probably very proud of its durability and driveability. But what about its air conditioning abilities? If you've ever had the car's AC system converted to R-134a refrigerant, you may have noticed some lessening in its cooling power. This, unfortunately, occurs in many cases of adapting, and it can be due to one of the following causes.

1. The refrigerant has been slowly leaking out of the system.

If you've done any research on the differences between R-134a and the refrigerant your car was designed to use (R-12), you'll know that the molecules of R-134a are smaller and can fit through smaller spaces. This means that a system designed for R-12 isn't necessarily R-134a-tight. Not only can it leak out of smaller holes that the original refrigerant may not have even noticed, but in some cases it can also leak right through the walls of the hoses in your AC system. If this is the case, you'll probably notice it sooner rather than later. It doesn't mean you have a catastrophic hole in the system, it just means you need to get the hoses replaced.

2. The compressor isn't strong enough for the refrigerant.

Another difference between the old refrigerant and the new is that their ideal operating pressures are different. The R-12 may operate ideally at the pressure created by your car's system, while the R-134a may struggle because the pressure isn't high enough. This doesn't mean the new refrigerant is itself "less efficient," it just means it's operating under less-than-ideal conditions. In cars with compressors designed for R-134a, it cools just as well as R-12 does. If your compressor size is the problem, you may want to pursue a different type of refrigerant for your system.

3. The system wasn't thoroughly drained before the new refrigerant entered.

If you don't flush the system before adding 134a, you can have big problems. It's not that the two refrigerants are incompatible; the problem is that the oils used with them must not be combined, or they create a jello-like substance that will block lines and possibly even clog the system, causing it to fail. If this has happened, your system needs mechanical attention right away.

These are just three of the perfectly reasonable explanations for a car that's been converted to R-134a and now doesn't cool as well. So don't blame the refrigerant; blame the conversion job, and have your mechanic, one like Malibu Motors Service, look at it to figure out how to improve the cooling potential.