A/C - r12 and r134a -- to mix or not to mix

[ScottieInBoca]

Second issue I am trying to work on this weekend is the A/C - just not all that cold -- fine at night, but incapable of cooling the car down after it has been sitting out in the hot sun.

Checked with the P/O's mechanic and the car has never been converted from r12. He advised that he has topped off r12 systems with r134a "hundreds of times" without any of the problems that I have found on the internet (leaking seals, damaged compressors, etc.)

The alternative is to completely purge the system and replace ALL the r12 with r134a. A bit more of a project and everyone indicates that the full purge will result in significantly degraded A/C performance.

So ... has anyone tried to mix r12 and r134 -- was it successful? Were there any long term consequences? Has anyone just given in and done the conversion -- how badly was the A/C performance degraded? Does it make the A/C system too ineffective to be practical?

Finally, and on a somewhat different note - I also have a leak from the condenser onto my foot. Does anyone have the A/C schematic so that I can figure out which tubing is damaged / missing and where it should be running to and from?

Scottie

[Wodnek]

This won't answer your mixing question.

The fact that it is still blowing cold, should tell you that the system itself is still in good shape.

R12 is still available. Why not just have it topped off with R12? It actually isn't that expensive and it works better in a R12 system then any other refrigerant. This way you won't have to experiment on your car.

[rowdie]

Don't mix refridgerants and clean the drains from below. Back ones are the heater/evap drains. Front are the blower motor housing.

[abiby]

Scary knowing that mechanic mixes R12 & R134

[SunGuy]

Originally Posted by abiby

Scary knowing that mechanic mixes R12 & R134

You mean ScottieInBoca's former mechanic. I'd drop that guy like a bad habit.

And Scottie, I'm in Bradenton, and with summer here in FL, it does take 3-5 minutes on full blast to to cool mine off when it's 95/95 and the car's been sitting for a couple hours.

Bob

[RadioTek]

!


DO NOT MIX R12 and R134 !!!!!

Sorry to shout, but this is important. There are chemical incompatabilities between the Freon-like compounds and the compressor lubricating oils. This has reputedly resulted in a condition of automotive air conditioning systems called Black Death. Where the heat combines with chemical reaction products to sort of 'powder coat' the interior of all components of the system. Bad Juju.

Spend the extra to get your system properly converted, or get some R-12.

It only cost $125.00 to get my pickup converted, so you may want to shop around for a mechanic that really knows what they are doing. It may not be as painful as you think.

Again, sorry about the shouting.

Scott

[LandYaghtLover]

I agree on getting it topped off. Although refrigerant never, ever "wears out" or "goes bad". And it never gets "used up" over the years. A lot of mechanics like to say that. What always happens when it gets low is that a leak has formed, its the only way the system will start to loose cooling capacity. However, if its minor you can get by with a couple top offs. In a year or two, you will have to locate and repair the leak.

[meltedpanda]

only if you want to blow yourself up!
nuf said

[AlanTbird]

Im my experience, the oil is the problem and dont remember which one is NOT compatible with 134. Its the EPA that says dont mix them. I always put R-12 in an R 12 system.
Just gave the SDL a drink in the spring and it FREEZES me out!
Tried freeze 12 in the Jag once and it wasnt too bad but R-12 is still the best!
Is all over e-bay and REAL cheap in mexico!

[tjts1]

So much BS. Mix all you want. Nothing will happen.

[Lee Wireless]

http://www.aa1car.com/library/retrofit.htm This article is from a "reliable" source. Don't mix or pay the consequences.

[samiam44]

easy,

R-12 will carry mineral oil or ester.
R-134a will carry ester or PAG. PAG is not compatable with mineral.

So, when you top up a system, you ussually add an ounce of oil. If you just top up a mostly empty system with R134a- the compressor will die due to lack of oil. Must add some ester.


M

[zeen]

I have put 134a in with R12 on a few older cars that I didn't want to invest too much in and didn't mind taking a little risk, with no problems. Two years and counting on my daughter's 1990 Volvo 740 with no ill effects, and it's doing a great job with this hot, humid summer we've had in Detroit. But if it's a car you care about and will be keeping for a while, there are really two scenarios:

- It's a minor seep with the passage of time on 15+ year old car, in which case you top it off with R12

- It's a major leak which requires cracking open the system to fix, in which case you should go ahead and do a proper conversion to 134a. You can't beat R-12, but 134a is cheaper, more environmentally benign, and works well enough.

[bwd111]

Originally Posted by LandYaghtLover

I agree on getting it topped off. Although refrigerant never, ever "wears out" or "goes bad". And it never gets "used up" over the years. A lot of mechanics like to say that. What always happens when it gets low is that a leak has formed, its the only way the system will start to loose cooling capacity. However, if its minor you can get by with a couple top offs. In a year or two, you will have to locate and repair the leak.

NO- POE AND MINERAL oil dont mix! That is just crazy