Freon question
Le Mans Master
Joined: Feb 2014
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From: Richardson Texas
Keith,Here’s the short answer:
✅ HC-12a can be used as a replacement for R-12, but there are some important caveats.
✅ HC-12a can be used as a replacement for R-12, but there are some important caveats.
🔧 Compatibility
- HC-12a is a hydrocarbon-based refrigerant (mostly propane/isobutane blend).
- It is compatible with the mineral oils used in R-12 systems, so you usually don’t have to change the oil or make major system modifications.
- You must completely recover all R-12 before adding HC-12a — you cannot mix them. Mixing R-12 and HC-12a can cause pressure and lubrication problems and is illegal under EPA rules.
⚠️ Legal and Safety Considerations
- HC-12a is not EPA-approved for use in automotive A/C systems originally designed for R-12 or R-134a in the U.S. (it’s considered a “flammable substitute”).
- It’s legal in some off-road, agricultural, or stationary refrigeration uses, but not in on-road automotive A/C under current EPA regulations.
- It’s flammable, so extra caution is needed during charging and servicing.
⚙️ Practical Use (if legally permitted)
If used in a setting where it’s allowed:- Recover all R-12 (don’t vent it).
- Evacuate the system completely.
- Charge with about 35–40% of the original R-12 charge by weight (HC-12a operates efficiently at lower pressures).
- Label the system clearly as containing HC-12a.
Le Mans Master
Joined: Feb 2012
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From: Western Massachusetts
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Given you must evacuate an R12 charged system prior to charging with HC-12A I recommend using 134A even if that means the minor hassle of changing the oil to ester (poe), which can be used with R12 or HC-12A should you decide to go with it later.
Why? Because to my knowledge no AC shops have a recovery rig for HC-12A and don't want to contaminate the rig they have. Few have an R12 rig. Everybody has a 134A rig though those will begin to disappear now that 1234YF is here and which is flammable don't you know.
134A will cool as well as R12 in a system otherwise in perfect operating condition. I have 6 air conditioned antiques to prove it. Properly charged into a tight, dry, deep vacuum 134A will function indistinguishably from R12 (or HC12A). It will make your life easy. If your system is tight, you won't need to worry about it. I have a 62 Bonneville, same system as a Corvette, running the same 134A charge since 2008 and it blows 38F.
Dan
Why? Because to my knowledge no AC shops have a recovery rig for HC-12A and don't want to contaminate the rig they have. Few have an R12 rig. Everybody has a 134A rig though those will begin to disappear now that 1234YF is here and which is flammable don't you know.
134A will cool as well as R12 in a system otherwise in perfect operating condition. I have 6 air conditioned antiques to prove it. Properly charged into a tight, dry, deep vacuum 134A will function indistinguishably from R12 (or HC12A). It will make your life easy. If your system is tight, you won't need to worry about it. I have a 62 Bonneville, same system as a Corvette, running the same 134A charge since 2008 and it blows 38F.
Dan
Thread Starter
Team Owner
Joined: Feb 2003
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From: Sitting in his Nowhere land Hanover Pa
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the only reason for the question was we found some of the HC 12A local for cheap. and wondering why it was cheap. but it seems its clear.
Race Director
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From: Mustang OK
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I solved the problem.
MANY years ago (when I saw the writing on the wall), I started accumulating R12. Now I have an R12 inventory that will long out last me! Several tanks and a few cases of 12 cans.
MANY years ago (when I saw the writing on the wall), I started accumulating R12. Now I have an R12 inventory that will long out last me! Several tanks and a few cases of 12 cans.
