Carpokes Porsche Forum

I am in the process of refreshing the AC on my car. The prior owner had the car "converted" to 134A last year. Looking at the shop invoice and description of service, it looks like they removed the R12. Pulled a vacuum for 10 minutes changed the hi and lo ports and put 134a in. They never even put the new refrigerant label in the car. So, no new dryer or anything. The AC at this point does not work. I purchased a new compressor, dryer, condenser and Griffith barrier hoses.

The Griffith hoses only supply a place to fit one of the two pressure switches so I am thinking the port on the dryer can be used. It has been suggested that the pressure switch for the fan is redundant and not needed. I don't think this is correct as that switch turns the fans on as soon as the AC is turned on to get air over the condenser. Am I correct in this?

I see many use Ester 100 as the new lubricant. I also read elsewhere that this to too viscous for newer compressors like the Denso I purchased from FCP Euro. Do I need Ester based on what I am replacing?

I am good at working on cars, but the AC is not an area I touched before since I do not have refrigerant recovery capability.

Thanks for any insight!

If it’s been converted to 134a do not add any / more oil. R12 (mineral oil) and 134 (PAG/ester) will gunk up your system when mixed. There’s already enough oil in the system from the past refrigerant swap.

Assuming the new compressor is filled with 134a oil, removing the old compressor and replacing the new will balance out as an oil change.

A quick work around is to use es12a / envirotech refrigerant that works with r12 or 134a refrigerant. It does not require the system to be pumped into vacuum before installation and preforms as well as r12.

Do not overfill with es12a. It only takes about half the amount of product. It also runs cooler, more efficiently and will not create acid if moisture gets in the system. That means less drag on the motor, less compressor operational time so better mileage, less wear and cooler air.

ES-12a refrigerant is illegal in the United States, specifically as a replacement for R-12 in vehicles, and its use in public transport vehicles has been banned since 1990. ES-12a is a flammable hydrocarbon refrigerant, and while it may be used in some industrial applications, its use in many common applications is restricted or prohibited.

Im at the tail end of doing this as well. I used esther oil because its compatible if there is any left over r12 oil. PAG oil is not compatible with the mineral oil. I also bought the 2 griffiths hoses and have a place for both switches? Not sure what set you bought.

I replaced compressor, condenser, 2 hoses and the drier flushed the rest. Changed all the O-rings to the green ones.

seiplej wrote: Wed Jul 16, 2025 7:39 am Im at the tail end of doing this as well. I used esther oil because its compatible if there is any left over r12 oil. PAG oil is not compatible with the mineral oil. I also bought the 2 griffiths hoses and have a place for both switches? Not sure what set you bought.

I replaced compressor, condenser, 2 hoses and the drier flushed the rest. Changed all the O-rings to the green ones.

+1 to all this. gramicci, Sounds like that hose is just the wrong one. In the long you'll be better off just replacing it with the one you need.

Interesting and thank you for the heads up on es12a being pulled. It’s still in my Corrado g60 from the years it wasn’t banned. There’s 3 or 4 others that have moved in to take its place and still outperform 134a.

The P cars and hi-po turbo / supercharged engine bays tend to heat soak. When the 134a can’t expel the increased load from heat soak, the a/c drops out or marginalises a/c performance.

A quick look shows Redtek 12a, r437 & r24 replaced es12a. All have almost a 30% efficiency increase over 134a. My previous commute was LA’s world leading parking lot traffic jam. 100*+ day, 90% humidity, triple black car, radiant heat and the scroll set for 1 bar toasted everything in the bay.

That’s an extreme set up and uncommon, but for those of us who ride the edge with upgraded engine
mods, that 30% jump in efficiency means normal a/c operation vs a sweatbox and potential engine overheat.

There are still many hydrocarbon r12 and r134a substitutes floating around for sale, but none are allowed as a retrofit for use in cars under the EPA rules. Most of them don't get pulled from the market, since they do have lawful uses, just not in cars. On quick review, Red Tek 12a is advertised as a hydrocarbon, and so would appear by definition to be unacceptable under the EPA's rules to use it in a car a/c system. Hydrocarbons are a fire/explosion risk. Sketchy companies try to skirt around and get 'cute' with their advertising to imply/suggest it's all ok, or add a footnote saying it's not for cars, etc., but they know darn well what they are doing. Red Tek sites a 1994 EPA rule dealing with non-ozone-depleting refrigerants, and uses that to claim EPA approval is not needed since hydrocarbons are not ozone depleting. They don't mention that hydrocarbons were address specifically under the EPA's SNAP program due to their fire/explosion risk. One of the more brazen sellers out there in my opinion. Buyer beware.

For what it's worth, I have an oversized turbo engine in my 944, and have a/c temps well into the 30's on hot California days, using r134a, a parallel flow condenser, and lots of attention to detail. There's really no need to fill your a/c system with propane or other explosives....

Frightening. Interwebs replied to my inquiry for “es12a replacements” precisely, but without the caveat you included. Thanks again.

Well, I guess if you’re going to go big and show you’ve been away from the refrigerant gas game, I pulled a bomb hand to prove it.

ES12 was marketed as an r12 replacement by Enviro-Safe. Like they all seem to do, they also touted the lack of ozone depleting substances and marketed it as a cheap and effective replacement for r12. They also failed to mention that it was a bomb in a can. But, Karma being what it is, they blew up their own building in 2013, before the government fined them and forced them to stop advertising it as safe and/or as an r12 substitute for cars. It didn't really stop them though, they still sell it, but now with tiny flammability warnings on the bottle and claims that it is a 'booster' only. Apparently, it doesn't take too much capital to put propane in a can, so these company's keep popping up with all the same claims, at least until they blow themselves up or the government reels them in.

https://www.gwclaw.com/blog/plant-explo ... -injuries/

https://www.coolingpost.com/world-news/ ... -for-300k/