Mercedes-Benz AC Service

As summer approaches, we all know what’s coming: air conditioning repairs. Just as you’ll outsell your wipers on a rainy day, you’ll never see more air conditioner complains than on a hot, sunny day. As a former Mercedes-Benz technician, I can tell you that AC complaints are very common in dealerships. So, what do you need to know about R-1234yf refrigerant in Mercedes-Benz vehicles?

What is R-1234yf?

To explain why we see R-1234yf becoming the industry standard refrigerant, we first need to talk about its global warming potential (GWP). According to the EPA website, “GWP was developed to enable comparison of the global warming impact of various gases. Specifically, it is a measure of how much energy the emission of 1 tonne of gas will absorb over a given period of time. The greater the GWP, the more certain gases warm the Earth compared to CO₂ during that time period. The usual timeframe for GWP is 100 years. GWP provides a common unit of measure, which allows analysts to add up emission estimates of various gases…”

So, policy makers and automakers want to reduce the carbon footprint of cars around the world. One way of doing this is by switching to a refrigerant that is less harmful to the environment than the R-134a that comes out. How dangerous is R-134a? It has a GWP rating of 1430. R-1234yf has a GWP rating of 4. You read that right, FOUR. With more and more vehicles on the road today, it makes sense for automakers to adopt these greener refrigerants.

R-1234yf only survives for 11 days in the atmosphere compared to 13 years for R-134a. This, as well as the GWP rating, is why the EPA is requiring automakers in the US to use R-1234yf in all new systems by the 2021 (MY) model year. It is important to note that some automakers are using R-1234yf as early as possible. MY2014 to offset the EPA penalty. So, R-1234yf isn’t new, but it’s still a bit new, and not everyone has worked on vehicles with this type of refrigerant.

What Does This Mean to You?

Mercedes-Benz seems to have started switching to the R-1234yf system, at least on European models. Here in the US, it is likely that some models will receive an updated system prior to MY2021 mandate. This means you should pay attention to the R-1234yf label under the hood, as it will impact how you quote and perform repairs.

R-1234yf comes at a higher price when compared to R-134a, but the exact amount will depend on the amount you buy and where you live in the country. This is another reason why it is so important to know exactly what type of refrigerant you are using BEFORE you quote the job.

As for the operating pressure, they are very similar. The R-134a system should register slightly lower pressures during operation than the R-1234yf system, but they must be within a few percentage points of each other. This is nothing compared to the proposed R-744 (CO₂) a cooling system that will run as much as 100 bar on the high side of the circuit!

Special Tool R-1234yf

It almost goes without saying that you should invest in a refrigerant extraction kit designed to handle the newer R-1234yf refrigerant. R-1234yf and R-134a fittings come in different sizes, but there are adapters out there that allow R-134a hose to connect to R-1234yf systems. We bring this up because we all know that sometimes our customers are just in the dark.

For example, if your customer is going to buy this adapter and is trying to refill their R-1234yf system with R-134a refrigerant, it could be a huge headache for you. This is why we would recommend investing in an external tester that can identify the type of refrigerant present in the system before attaching your expensive extraction machine.

Many R-1234yf extraction machines will weigh the extracted refrigerant, then apply vacuum to the system and hold it for 20-30 minutes. This is an important step and should not be skipped! Instead, monitor the vacuum level in the system and see if it changes over time. This will indicate a leak somewhere in the system, and the machine may not let you charge the system if this is the case. This is to protect the environment, as well as your operational costs.

We also recommend purchasing an external filter that can be attached to the hose set prior to the extraction machine. This gives you one more line of defense against any contaminants or debris that may be in the system, and protects your expensive extraction machine from damage. This is especially important when working on vehicles with compressor failure, which can introduce metal debris into the system.