Major changes to au­to­mo­tive air­con­di­tion­ing sys­tems

Motor Equipment News - - KEEPING IT COOL -

Major changes to leg­is­la­tion will see the en­sur­ing au­to­mo­tive air con­di­tion­ing in­dus­try stan­dard re­frig­er­ant, R134a, phased out of use in new ve­hi­cles over the next few years.

As is tak­ing place in the Euro­pean Union and United States, the HFC phase-down will ac­cel­er­ate, and even­tu­ally man­date, the switch to low-GWP re­frig­er­ants in the air con­di­tion­ing sys­tems of new ve­hi­cles.

In fact, a grow­ing num­ber of ve­hi­cles im­ported to New Zealand and Aus­tralia from mar­kets where a phase-down is in place are already on our roads and the end of local car man­u­fac­tur­ing this year will add mo­men­tum to the up­take.

Since the ozone layer dam­ag­ing CFC re­frig­er­ant R12 was phased out in the mid-1990s, the only re­frig­er­ant used by ve­hi­cle man­u­fac­tur­ers has been R134a.

With cli­mate change now on the agenda, ve­hi­cle air con­di­tion­ing sys­tems us­ing R134a are be­com­ing a thing of the past be­cause R134a is around 1,300 times more po­tent than car­bon diox­ide as a green­house gas if re­leased to the at­mos­phere.

For com­par­i­son, R12 is 10,900 times more po­tent than car­bon diox­ide as a green­house gas, in ad­di­tion to de­stroy­ing strato­spheric ozone.

Both R1234yf and R744 are ozone-friendly, and have global warm­ing po­ten­tial of be­low or equal to car­bon diox­ide.

Much of the global au­to­mo­tive in­dus­try has adopted R1234yf as the stan­dard re­frig­er­ant in new cars, pri­mar­ily due to tight­en­ing over­seas leg­is­la­tion over the global warm­ing ef­fect of re­frig­er­ants re­leased into the at­mos­phere.

Un­like the switch from R12 to R134a there will be no need to change ex­ist­ing air con­di­tion­ing sys­tems over to R1234yf, be­cause R134a will con­tinue to be avail­able for ser­vic­ing older equip­ment.

Due to sim­i­lar ther­mal prop­er­ties be­tween R134a and R1234yf, faults with sys­tems us­ing the new re­frig­er­ant can be di­ag­nosed us­ing the same meth­ods as R134a.

R1234yf car­ries an ASHRAE rat­ing of A2L (mildly flammable) and is sub­ject to Dan­ger­ous Goods class han­dling and trans­porta­tion re­quire­ments.

How­ever R1234yf is not eas­ily ig­nited and strug­gles to sus­tain and prop­a­gate a flame com­pared with A3 (highly flammable) rated re­frig­er­ants avail­able to the af­ter­mar­ket but never used or ap­proved by OEMs.

To en­sure safety, new SAE stan­dards ap­ply to the qual­ity of sys­tem com­po­nents and the equip­ment used to ser­vice R1234yf sys­tems. Some equip­ment is rated as com­pat­i­ble with both R134a and R1234yf and some equip­ment is suit­able only for R1234yf.

Mercedes-Benz par­ent com­pany Daim­ler and Volk­swa­gen Group have de­vel­oped sys­tems us­ing a car­bon diox­ide as a re­frig­er­ant (named R744) that will ini­tially be used for high-end ve­hi­cles.

R744 re­quires op­er­at­ing pres­sures up to 10 times higher than R134a or R1234yf.

Back street re­gassing will soon be a thing of the past. Pic­ture Wikipedia/ Mike Peel (www.mikepeel.net).

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