View Full Version : R600a as drop-in for R12 in car ac?

04-06-2009, 07:50 AM

first of all, I'd like to introduce myself. I am a student currently living in Australia and will go back to Europe later this week. At home, I do have an old Mercedes car with an ac that never worked. I'll overhaul the ac next winter to enjoy it in summer 2010. Here in Australia I learned that some people use mixtures of propane and isobutane in their AC as a replacement of R12. I know that there is no real chance to get these blends in Europe. But there is plenty of refrigartion quality R600a available. My question is: Can I use pure R600a instead of this blend? The AC is an expansion valve unit, just as an additional information if this matters.



04-06-2009, 07:59 AM
You can, provided appropriate calibration in refrigerant charge and TXV settings are taken into account. Please also consider the opportunity to fill your car a/c with a flammable vapour, that can represent a flame enhancer in case of accident.

04-06-2009, 08:14 AM

I am well aware of the flammability and would like to thank you for mentioning it again!! This is very important

Less charge is OK. I have read about it somewhere and bookmarked the page on how to calculate the refigerant quantity.

What I do not understand is how to modify the TXV. This is a small Aluminum block, nothing to adjust there. What do I have to do with the TXV or what would happen if I don't do any modifications to the TXV?


04-06-2009, 09:30 AM
I was under the impression that fitting inflammable refrigerants into car A/C was banned from the safety aspect. A small leak from the evaporator and then you use the cigar lighter and things could get extremely noisy in the cabin.
It would be best and wisest to use one of the tried and tested R12 replacements, either R413A or RS24. These work without change of oil or any other major adjustments. You may need a slightly smaller quantity of refrigerant charge than R12. Suggest that you check with the refrigerant manufacturers. Always err on the side of safety.

04-06-2009, 10:25 AM

again, everybody warning about the dangers of flammble refrigerants is right. I have to admit that I most likely have too much respect as to really use them, anyways. On the other side, I am curious enough to see how they work. My actual plan is to fix the ac and fill it with R600a just to see if it works. Afterwards, I'll recharge it with R413A for safety reasons.
So my open question remains. How can I adjust one of these TXVs that basically look like a box of cigarettes made of Aluminum?

04-06-2009, 11:27 AM
I can't help on regard of TXV. It may well be a proprietary lamination device....

04-06-2009, 01:49 PM
On most of the TXV fitted to cars, there are little or no adjustments available.
Experimenting with R600a should not be an option.

05-06-2009, 01:29 AM
dont do it ,you are trying to put r600 into a system as an experiment crazy if pou do it ring the police etc so they can evacuate hasnt oz just had fire tragedy,

06-06-2009, 12:22 AM
The R134 A its not available in Australia?, just change the oil and you can safely retrofit the AC unit