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The next time you visit your local Chrysler, Dodge, Ram, Jeep, Fiat dealership you may notice an under hood sticker with the notation of a refrigerant called HFO1234yf on most of the new vehicles. What is this? Is it a misprinted sticker? Is it a new refrigerant? What happened to R-134a?
It is not a misprint, but rather it is a new refrigerant that Fiat Chrysler Automobiles (FCA) has embraced while many other automobile manufacturers are limiting their change over to the new refrigerant at this time. The new refrigerant better known as R1234 (pronounced R, twelve, thirty-four) has been designed to reduce the Global Warming Potential (GWP) concerns of the current R-134a refrigerant.
Before we get in depth about the newest refrigerant, here is a little history about automotive cooling methods. The earliest occupant cooling methods of a vehicle included having the top retracted, a windshield propped open at the base, the windows rolled down, or the kick-out louvers opened in the foot box area of the car. Regardless of the cooling method(s) selected, all of these cooling options required vehicle movement; none of them provided air filtration, and all provided poor cooling on hot and humid days.
The next step in the evolution of automotive cooling prior to the use of mechanical refrigeration systems was the installation of aftermarket passenger-side window mounted evaporative coolers. This system consisted of a cotton swab attached to a bobber that floated on the surface of water housed in a cylinder. A string attached to the swab was pulled to submerge the swab in the water, and the bobber pulled the swab back to the surface. As the vehicle was driven down the road, the wind blowing around the vehicle would enter a scoop attached to the unit on the window. The airflow was directed over the surface of the wetted swab and into the vehicle. The airflow caused the water to evaporate providing a sensation of cool air entering the vehicle. When the cooling became less efficient, a quick pull of the string would re-wet the swab and the cooling would again improve. This only worked when the vehicle was in motion, although some high dollar evaporative cooler units provided a small 6-volt motor that would blow the air into the vehicle even when there was no vehicle motion. To increase the evaporative cooling, a mixture of alcohol and water could be employed. Regardless of what liquid medium that was used, on a high humidity day this system was useless, and as with the windows down option, there was no air filtration provided by this system.