# Auto A/C

**URL:** <https://boards.straightdope.com/t/auto-a-c/89254>\
**Category:** Factual Questions\
**Created:** [October 24, 2001, 4:23am UTC](https://boards.straightdope.com/t/auto-a-c/89254 "2001-10-24T04:23:48Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![handsomeharry](https://avatars.discourse-cdn.com/v4/letter/h/e9c0ed/32.png) [@handsomeharry](https://boards.straightdope.com/u/handsomeharry)\
**Post date:** [October 24, 2001, 4:23am UTC](https://boards.straightdope.com/t/auto-a-c/89254/1 "2001-10-24T04:23:48Z")

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Coolant for A/C Retro fitting, to my understanding, means exchanging r12 with 134a (or whatever)…so, my question is, can i myself buy a new compressor for r12 and fill it with 134a and save myself a buttload of money? Are there web instructions for this anywhere?

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**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\
**Post date:** [October 24, 2001, 4:37am UTC](https://boards.straightdope.com/t/auto-a-c/89254/2 "2001-10-24T04:37:57Z")

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You really aren’t supposed to do that. The old R12 has to be disposed of in a very specific way and you’ll be paying an enormous fine if you’re caught dumping old refrigerant down the drain. It’s more trouble than it’s worth.

Haj

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**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\
**Post date:** [October 24, 2001, 5:29am UTC](https://boards.straightdope.com/t/auto-a-c/89254/3 "2001-10-24T05:29:33Z")

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> [@](#):
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> …You’ll be paying an enormous fine if you’re caught dumping old refrigerant down the drain.

What are the fines for violating the laws of physics? Freon is a gas at room temperature and pressure.

That said, there are A/C discussion boards out there. Unfortunately, I don’t have any links. For what it’s worth, if you have a good compressor, you may be able to drain the old oil (which has R-12 diffused into it), flush and evacuate the system and refill with new oil and R-134.

…And _that_ said, a lot of places advertise this service for about the cost of a few cans of R-12. They also handle the R-12 recovery so the stuff doesn’t escape. You might want to have them evacuate the system, then troubleshoot it yourself.

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**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\
**Post date:** [October 24, 2001, 12:17pm UTC](https://boards.straightdope.com/t/auto-a-c/89254/4 "2001-10-24T12:17:12Z")

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I’m not sure I understand but from what I know you can just use r134 instead of r12 with r134 oil (the old 12 oil stays in the system and just floats above the 134 oil - the 2 actually can’t mix). You use the same compressor.

So yes you can use 134 w/ a new r12 compressor but unless you actually need the new compressor you don’t have to replace it.

cooling efficency will decrease w/ 134 though.

there is no disposal problem except for venting r-12