A/C R-12 to R-134

[aljordan]

I'm faced with this as I was pulling the motor and broke a line (solder joint between the larger turbe and the metal line on the right side of the radiator). Line just started hissing. I figure I'd replace all the o-rings in the system since I don't have any (or very little) R-12 in it. In fact, I can turn on the AC, and nothing happens. Not enough in it to let the compressor run. Should I have it evacuated or just crank it open and not worry about it. Its not like the guy is going to give me credit for the R-12 that I give to them.

About how much is it going to run me to fill this sucker back up with R-12???

 

[jetjock]

If the system has been open to air for any length of time you need to replace the receiver dryer. Fix the break, replace any O rings on connections that've been opened (you sould lube them with a bit of mineral oil or one of the products made for that) and then have the system pumped down and leak checked.

If tight pump it for at least 30 minues more and charge with whatever the manual says. Around 2 pounds I think. It's on the label under your hood. last I checked cost for R12 at a shop is around $45-55/pound or so these days. If you do the work yourself all you'll have to pay for is the R-12 and maybe a bit of labor.

I'll point out what I have before: A/C system longevity is directly related to the quality of work done and parts used. The more you do things right the longer it'll last. If the system is old then rebuild it. Replace the compressor, flush the system, and go from there. It can get expensive but with A/C it's either do it right the first time or do it again. Generally speaking unless you can do the work yourself and are certified to buy refrigerant there is really no cheap way out and still have it work a long time.

Good reason to learn me thinks. Start by buying the Haynes book available at most auto stores, get your cert, and invest in a manifold set along with a few other tools. This goes for you too 5MGTE. It's not that hard or expensive unless you go nuts and it'll set you free.

Or just rip the system out as many do. Be a man...only pussies need A/C right?

 

[aljordan]

My system has been open for about 6 weeks. New receiver dryer??? I hope not. That's tearing the dash apart. There is still some R-12 in the system as I can remove one of the port covers and hit the schrader (?) valve and I'll get a some pressure release.

Prior to this.. the system was excellent. The only time it would lag would be when it was 95° outside. Other than that.. it blew ice cold. No recharges in the past 10 years either.

 

[jetjock]

I don't understand how you could've fractured a line and still have refrigerant in the system. Either you had a leak or you didn't. R-12 will get out a leak like that and keep going until the system is empty. For sure it'll do it in a hot engine compartment. However if you still have refrigerant in the system the receiver/dryer won't have been exposed to the atmosphere and replacement may not be needed.

It's still good practice to replace it if it's been in there for a long time though. I know I'd do it if it were my car. It's in the left front grill of the car btw, not in the dash. The thing with the sight glass on it. Pretty easy to change. You must be thinking of the evaporator. I don't know about evaps but for sure heaters cores are no fun on the MKIII.

Don't expose a new receiver/dryer to air (don't remove it's caps) until it's time to be installed in a system that's ready to be evacuated. The r/d has dessicant in it. One of it's two jobs (the dryer part) is to remove water, the main enemy of A/C systems. No matter how well you evac a system there will always be some water wapor left and the r/d takes it out. As soon as you remove a new ones' caps it'll start sucking water vapor out of the air like a sponge.

 

[Allan_MA70]

over here r12 is still in use for commercial fridges

 

[tissimo]

k cause im painted the engine bay, going to pull everything and replace all the seals put a new dryer on and new rubber lines to the compressor (1jz swap), so hopfully should be good for hot summers here in fl

 

[johnathan1]

*sigh* JetJock...don't be ashamed of me...I used an Autozone R-134a conversion kit ...but damn, the A/C blows cold as hell now

 

[jetjock]

Hey, a guy has to do what a guy has to do.

I'l have a look next time I'm at AZ but I've never said death kits don't work. What I've said is if the oil didn't get changed or the kit "cheated" it you're living on borrowed time and when the compressor fails from lack of lubrication it's going puke it's guts into system.

That'll for sure mean a new compressor, complete flush, receiver/dryer, probably a new condensor and, if you're really unlucky, a new expansion valve. That means the evaporator will have to come out (dash gets torn apart). Even if that doesn't happen you'll be staring at over a grand with labor. I give it a year or two tops. If you use the AC a lot, probably less.

It's simply a matter of pay now or pay later. You chose to pay (a lot more) later. But at least you'll be cold right up unitl it happens

 

[johnathan1]

Hey, a guy has to do what a guy has to do.

I'l have a look next time I'm at AZ but I've never said death kits don't work. What I've said is if the oil didn't get changed or the kit "cheated" it you're living on borrowed time and when the compressor fails from lack of lubrication it's going puke it's guts into system.

That'll for sure mean a new compressor, complete flush, receiver/dryer, probably a new condensor and, if you're really unlucky, a new expansion valve. That means the evaporator will have to come out (dash gets torn apart). Even if that doesn't happen you'll be staring at over a grand with labor. I give it a year or two tops. If you use the AC a lot, probably less.

It's simply a matter of pay now or pay later. You chose to pay (a lot more) later. But at least you'll be cold right up unitl it happens

Wow, that makes me feel A LOT better...thanks JetJock!

 

[IHI-RHC7]

Thanks for the Info Gary, we're sitting two years on a death kit, but it included oil. the only thing I didn't do was hold the system in vaccum...
So that means that there was still probably some R12 in the system, and they aren't happy with one another at the moment. What, exactly, happens when there is remnants of unmiscable R12 mixed in with the proper amount of R134A?

 

[johnathan1]

my death kit came with the oil and refrigerant already mixed...(if that is possible) it said something like "R-134a Refrigerant with High-Mileage Lubricant"

 

[Nick M]

New receiver dryer??? I hope not. That's tearing the dash apart.

The reciever dryer is by the condenser. It should have sight glass on top of it. It is a high side component.

You might be thinking of the TXV. TXV is thermal expansion valve. It creates the pressure drop, lowering the refrigerant to extremely low temps.

 

[jetjock]

my death kit came with the oil and refrigerant already mixed...(if that is possible) it said something like "R-134a Refrigerant with High-Mileage Lubricant"

Johnathan, not only is that possible but thats what the entire death kit thing is about. The oil circulates with the refrigerant and lubes the compressor. 134 can't carry the old R 12 oil. The way death kits cheat is to come with oil in the refrigerant but now you have both the new and old oil in there. Not only are the two often incompatable with each other (depends on the kit) but too much oil in the system makes it's own problems. But as long as the 134 is carrying oil things won't blow up quickly.

It works "ok"...it's just not the way to do things. It could last 5 years or it could lunch next week. That's the problem and what makes it not worth the risk. And you gotta remember, you're talking to a guy who strives to do things right so I'm gonna be a tad biased.

 

[jetjock]

Thanks for the Info Gary, we're sitting two years on a death kit, but it included oil. the only thing I didn't do was hold the system in vaccum...So that means that there was still probably some R12 in the system, and they aren't happy with one another at the moment. What, exactly, happens when there is remnants of unmiscable R12 mixed in with the proper amount of R134A?

Jake, the system needs to be pumped to at least 28 hg for a minimum of 30 minutes. The lower the better. It helps to do it when the engine bay is hot. This is why I'm not a fan of venturi pumps. Pumping is all about getting water out, not old refrigerant. That's long gone before you even pull hard on it.

Water vapor is a polar molecule and one of the hardest gases to pump known. It's the bain of every vacuum system. Not only is it not a very good refrigerant but freezes in the expansion device, be it a TXV or an orifice tube. The worst thing is does is make acid. But if you pumped on the system at all the R 12 is gone. Even if it wasn't it isn't something to worry about. Nor will it hurt cooling much. It's still a refrigenrat you know, the one the system was designed for

That said, the key to AC performance is purity of the refrigerant. If your system isn't happy it's probably got some water or other "trash" in it, especially if the old receiver/dryer was left in. You'll have to be more specific for me to offer more than that.

*edit* I'll post these links again for anyone looking for help or info on MVAC:

http://tinyurl.com/8bmdw

http://tinyurl.com/ekp3u

 

[IHI-RHC7]

Thanks, Always sharin the edumacation.

 

[jetjock]

You too...I know a lot more about pulsation dampeners than I did yesterday

 

[IHI-RHC7]

Heh, any comments to my last FPD comment?