A little off topic AC conversion R12 to R134A.
- Thread starter perryg115
- Start date
https://shop.advanceautoparts.com/r/car-projects/how-to-convert-r-12-refrigerant-to-r-134a
This seems to generically cover your concerns.
This seems to generically cover your concerns.
This will get me flamed, but hey. On my old 91 Miata I used the Envirosafe ES12 (I think it was) which is a 'drop in' replacement for the R12. It is essentially a mix of propane and butane. It worked great while I had that car.
I forgot the legalities of it, something like it had to be 'converted' over to R134 first or something (Basically it had to have the R134 fittings on it). It's been 15 or so years so I'm a little foggy on it.
--Edit--
Looking at their site, it looks like they advertise theirs all as 134 replacements now. Probably due to the EPA I'd imagine, but if you read the specs it says they are compatible with most oils, which is what you'd be after. So you'd pop on the new fittings and charge with their product.
I'm sure I'm about to get screamed at, so FWIW on this one.
I forgot the legalities of it, something like it had to be 'converted' over to R134 first or something (Basically it had to have the R134 fittings on it). It's been 15 or so years so I'm a little foggy on it.
--Edit--
Looking at their site, it looks like they advertise theirs all as 134 replacements now. Probably due to the EPA I'd imagine, but if you read the specs it says they are compatible with most oils, which is what you'd be after. So you'd pop on the new fittings and charge with their product.
I'm sure I'm about to get screamed at, so FWIW on this one.
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Welcome to BITOG 
You don't have to get all the old oil out, but get as much out as you reasonably can. Ester oil is the best thing to use for converting to R134a. It is compatible with residual amounts of mineral oil that was used with R12.
You just need a set of adapters, some cans of R134a, and a can of ester. You can probably buy all of this included in a kit.
You don't have to get all the old oil out, but get as much out as you reasonably can. Ester oil is the best thing to use for converting to R134a. It is compatible with residual amounts of mineral oil that was used with R12.
You just need a set of adapters, some cans of R134a, and a can of ester. You can probably buy all of this included in a kit.
You also might want to pick up a can or two of a AC System Cleaner like this:
in order to flush the oil and some of the dirt out of the hoses and condenser.
in order to flush the oil and some of the dirt out of the hoses and condenser.
Fix the leak and shoot some Coleman's in it.
First things first, find and fix the leak. You can also check out R12 to R152A, the stuff used to dust off keyboards and such. I read about people using that with good success and there is no need to swap out the compressor oil. It is cheap and easy. I'm not sure of the legal ramifications though.
Remove it and pour it out
Most of the time it needs to be removed from the car and drained out the hp/lp ports unless there is an actual drain plug. A lot of Sanden and Nippondenso compressors have drains.
Fix any leaks. Replace all the orings you can. Change the dryer. Put on the retrofit adapters. Add the correct amount of Ester oil. Vacuum and charge to 85% of the r12 charge.
Are you anywhere near socal?
Are you anywhere near socal?
Not enough in it to worry about
Get some Red-Tek off ebay. Charge.
Red-Tex R12a (or equivalent ) in your situation.
Each 6oz can is equivalent to 18oz of R12.
Also - their Oil Charge 4oz can has 2oz of across the board compatible ester oil + 2oz of R12a (that's another 6oz worth of R12 OE fill).
So the above amount is about ideal for a 40-44oz R12 system.
Bonus - no need to vacuum/dry the system or drain old oil.
R12a is best filled at an atmospheric charge, works best in systems with a bit of moisture, and has far larger molecule size than R134a - minimizes leaks.
Performance wise - it's close to R12, and quite a bit better than R134a. Lower head temperatures to boot.
I've attached a pic of my R12 OEM fill - 32-33f vent temps.
Granted, only 75f ambient, but the vent temp doesn't climb above a blistering hot 35-38f at a 100f+ ambient.
R12a will only be a few degrees higher in equivalent ambients.
And it does well with existing expansion valves, condensers, evaps, pressure switches, compressor cycling switches/probes etc.
Each 6oz can is equivalent to 18oz of R12.
Also - their Oil Charge 4oz can has 2oz of across the board compatible ester oil + 2oz of R12a (that's another 6oz worth of R12 OE fill).
So the above amount is about ideal for a 40-44oz R12 system.
Bonus - no need to vacuum/dry the system or drain old oil.
R12a is best filled at an atmospheric charge, works best in systems with a bit of moisture, and has far larger molecule size than R134a - minimizes leaks.
Performance wise - it's close to R12, and quite a bit better than R134a. Lower head temperatures to boot.
I've attached a pic of my R12 OEM fill - 32-33f vent temps.
Granted, only 75f ambient, but the vent temp doesn't climb above a blistering hot 35-38f at a 100f+ ambient.
R12a will only be a few degrees higher in equivalent ambients.
And it does well with existing expansion valves, condensers, evaps, pressure switches, compressor cycling switches/probes etc.
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As far as I know, Denso compressors don’t have an oil drain nor a filling port like a Sanden and some Harrison/Delphi(and their clones Calsonic and Zexel/Valeo Japan made for Nissan and Subaru).
in the case of R-134a, the incompatible mineral oil will make its way to the lowest point of the system and stay there. In many cases, it’s the drier/accumulator.
In your case, try to get as much of the old oil out, install a new dryer, add in the prescribed amount of oil but in ester, evacuate and charge to 80% of the called for weight. Keep an eye on the high/low pressures.
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- May 17, 2021
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Before trying Red-Tex find and study the info on it. It's primarily propane, does indeed work well as a car refrigerant, but has the disadvantage that it's a gas at normal pressures/temperatures and highly explosive when mixed with air. So in using it in an automotive refrigeration system you're piping an explosive gas into a metal/glass box in which you'll be sitting. Any leak, say in a minor crash ...
The following link has a pretty good discussion and there's a YouTube video a few posts down with a demo of propane in a car:
Has anyone here used "Red Tek" 12a Freon/Refrigerant?
My '11 Acadia has a decent a/c temp, but I'd like to try and get it a bit colder. I know I should just check and top off what's needed, but I have been reading on Red Tek's site saying that their refrigerant operates at a lower head pressure, improved cooling properties and requires much less...
gmtnation.com
There's a reason it's not used commercially for car A/C.
JHZR2
Staff member
Especially while searching for leaks, this is a good idea. Most folks don’t have bone dry N2 with a trace of refrigerant to use as a leak check agent. This stuff works, has a pine scent which can be helpful for tracing leaks, and isn’t such a big issue as leaking halogenated hydrocarbons to the atmosphere.
Tge only thing is that direct use is called, as I recall, a sham retrofit. One is supposed to do a conversion to r134 first before using this stuff. So op should look into that concept first.
Once leaks are found and fixed, op can decide to use r-134, or revert back to r-12, which will probably do a bit better.
OP, an actual 134a replacement should probably include a new receiver dryer, new o rings in as many places as possible, potentially replacement of some hoses to a barrier type, Swap of the pressure cutoff switch, etc. the more areas changed, the better it will perform and last. I ran a quality 134 conversion in my 91 bmw for over 10 years.
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