Whats better? R-12 or R134A

R134a and R12 are not compatible and can not be mixed. When converting from

12 to 134a all the original oil must be removed, as it does not entrain in 134a and it reacts with the oil for 134a to form acids if any trace of water gets into the system.

I have little faith in R12 substitutes. I'm not an expert, but I suspect there's a reason they are not mainstream while R134a is. At least one substitute is isobutane - thermodynamically nearly identical to R12 but very flammable. A collision that punctures the condensor could be spectacular.

R12 will only get more scarce, since all the countries that signed the Montreal Protocol have banned its manufacture or importation. Only licensed servicemen are allowed to buy it, and the price (effectively black market) is outrageous. Yes, it does work better than R134a in systems designed for R12, but you don't want to do the full conversion to a true 134a system: compressor, condensor and evaporator.... Da-ching!

Short answer - stay with R134a in what you have and get the headaches behind you, instead of in front of you.

BTW, the ozone depletion scare for CFCs was laid to rest a full decade after we signed the Montreal Protocol - see

- but we still have to live with it.

Mike

Thanks Mike,

You been a real help. I am just wondering why my A/C isn't cold enough though. I am pretty sure new cars are all using the R134A correct?

My girl-friend drives a 2002 Mazda Millennium, and when her A/C is on it blows so damn cold that you can see a frost being sprayed out. [simlar to when your outside when its freezing outside, and you blow into the air, you see a steam]. If she is using the R134A, and her car is so cold.

Why won't mine get cold? it is only cold if I am on the accelerator. If I am sitting at a traffic light waiting for it to turn green. While I am waiting, its just blowing out cool air, but it really isn't cold. My air probably is around 78 degress coming out.

Is there anything that can be done to make my air colder? as you know the older cars don't have temperature gauges like the newer cars. With your typical newly designed car you can set the thermostat to a set temperature such as 71 degrees, but with less expensive cars you just push the sliding nob to the blue or red.

Thanks

More modern cars have the entire system designed for R134a. As I understand, it involves a different compressor and condensor, and possibly a different evaporator. The compressor and condensor are to accomodate the higher high side pressures R134a requires to pump the same amount of heat as R12 does. Running R134a in an R12 system definitely results in lackluster cooling - my '85 Volvo has that setup; works fine on the freeway, but not in town.

Mike

I'm certainly no expert but I would agree with Mike on this. We had a '93 Lincoln Town Car "converted" to R134a reusing everything but the dryer and it worked exactly as you describe. On the hottest days at idle speed the cooling was hardly what you would call "cool" but get rolling down the road and the performance was good. We had it checked a couple times (different shops) and never found anything wrong.

Does that mean our vehicle engines must consume more fuel to achieve the higher pressure?

No.

No - it's a complicated thing (I researched it a lot about 8 years ago) that results in roughly the same amount of energy being required to pump the heat pretty much regardless of the pressure difference. The actual pressures are the result of the pressure/temperature curve for each gas, and the actual compression energy required is more dependent on condensor temperature than on condensor pressure per se.

A factor slightly in favor of R134a is the "ratio of specific heats" - essentially a measure of loss as the gas is compressed and expanded. R12 is about 1.13 while R134a is about 1.09 (1.0 is perfect; air is about 1.4).

Mike