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Info guides and mods

Air Conditioning Gas Quantities

Modification Details




AC Gas Type And Quantity

Model Gas Type Gas Qty Grams Oil Type Oil Qty Millilitres
450 Fortwo 600cc R134A 620 ± 10 PAG 46 or PAO 68 180
450 Fortwo 700cc R134A 450 ± 10 PAG 46 or PAO 68 180
450 Fortwo Diesel R134A 450 ± 10 PAG 46 or PAO 68 180
451 Fortwo Non Turbo R134A 450 ± 10 PAG 46 or PAO 68 180
451 Fortwo Turbo R134A 450 ± 10 PAG 46 or PAO 68 180
451 Fortwo MHD R134A 450 ± 10 PAG 46 or PAO 68 180
451 Fortwo Diesel R134A 450 ± 10 PAG 46 or PAO 68 180
451 Fortwo Electric Drive R134A 500 ± 10 PAG 1234* 100
452 Roadster R134A 620 ± 10 PAG 46 or PAO 68 180
452 Roadster Coupe R134A 620 ± 10 PAG 46 or PAO 68 180
453 Fortwo Non Turbo (Nov 14 to Feb 16) R134A 475 ± 10 PAG 46 or PAO 68 180
453 Fortwo Non Turbo (Feb 16 onwards) R1234YF 475 ± 10 PAG 1234 180
453 Fortwo Turbo (Nov 14 to Feb 16) R134A 475 ± 10 PAG 46 or PAO 68 180
453 Fortwo Turbo (Feb 2016 onwards) R1234YF 475 ± 10 PAG 1234 180
453 Fortwo Electric Drive R1234YF 430 ± 10 PAG 1234 100
453 Forfour Non Turbo (Nov 14 to Feb 16) R134A 475 ± 10 PAG 46 or PAO 68 180
453 Forfour Non Turbo (Feb 2016 onwards) R1234YF 475 ± 10 PAG 1234 180
453 Forfour Turbo (Nov 14 to Feb 16) R134A 475 ± 10 PAG 46 or PAO 68 180
453 Forfour Turbo (Feb 2016 onwards) R1234YF 475 ± 10 PAG 1234 180
453 Forfour Electric Drive R1234YF 430 ± 10 PAG 1234 100
454 Forfour R134A 440 ± 10 PAG 46 or PAO 68 100

February 2016 (ish)

This date is the best I could get from smart. Looking at the AC pipes on the parts system, the swap over date is Feb 2016.

However, you should check your car before ordering any gas. It doesn't matter if you are
taking it to a specialist since (apparently) the connectors are different between the 2.

If you look carefully, at least 1 of the pipes at the front will state what gas it's designed for.



Gas Type

Since the beginning of the smart, the air conditioning gas type used was R134a.
The European Union decided that R134a was shit-in-a-can and it would single handedly destroy the world.

So they chose a replacement, made by Honeywell and was called R1234yf.
It had a far lower GWP (Global Warming Potential).

R134a has a GWP of 1430.
R1234yf has a GWP of 4.
Carbon Dioxide (CO2) has a GWP of 1.

In 2011, the EU made up new rules stating that all new car platforms must use R1234yf.
The 451 had already been released so smart weren't required to adapt it to use the new type of gas.

However, Mercedes, Audi, VW and BMW refused to use R1234yf for 3 reasons.

It is less efficient.
The system has to be at a higher pressure.
R1234yf is flammable.

The new R1234yf systems have to be more robust due to the pressure,
plus it has to not leak as easily in a crash.

So, for years, Daimler pushed back against the EU despite fines and legal threats.

Because of this, even when the 453 was released, it was still using R134a gas.
Mercedes aren't happy with having to use R1234YF and are looking at moving towards CO2.

Oil Type

To keep the compressor running smoothly and to keep the rubber O rings from
drying out, a percentage of the air conditioning system is filled with a refrigerant oil.

This oil is normally PAG 46 (Polyalkylene Glycol) but PAO 68 (Polyalphaolefin) is compatible.

PAG 46 is thin, PAG 100 is medium, PAG 150 is thick.

*However, oddly, on the 451 Electric Drive (ED), the car recommends PAG 1234.
This oil is specially designed for AC systems running R1234yf gas but as you can also see, it runs R134a.



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