A/C Question

[99screaminregal]

Ok, first car to have an old r-12 a/c system and I want to do the retro fit to r-134.

 

I know I gotta get a retro kit for it but, do I need to take it to a shop and have what's left of the r-12 sucked out? Or, should I just take it to that shop (that still deals w/ r-12, yeah I know, hard to come by) and get it recharged and not worry about the upgrade??

 

I was at Wal-Mart and the box I looked at doesn't exactly give the clearest instructions. Just how to put the fittings on and fill. Nothing about evacuating the system.

 

I know it would be cheaper to have the upgrade done but, I've heard that the old r-12 lasts longer and cools better, supposedly.

[RobertISaar]

R12 does cool better...

 

and those "conversion" kits from wal-mart only convert the fittings... supposedly, you're supposed to replace the condenser, evaporator and a whole bunch of other crap too to do it correctly...

 

"evacuating" the system is as easy as unscrewing the caps and putting a screwdriver to the valve. illegal as hell, especially if the EPA finds out. doesn't stop rednecks everywhere from doing it though.

 

then you're supposed to remove moisture from the system during this process with a vacuum pump...

[99screaminregal]

I think that's what pollutes most of my redneck town anyway.

 

Yeah, I do memer my friend had to replace all that shit on his bro's car to do that........ Might as well spend what I'd put in those parts and just have that shop do the r-12.

[White93z34]

I would like to actually see some evidence that r12 cools better, I think its a crock myself. I converted my z34 last year and its ICE cold.

 

Long and short of it, all you should need are the new fittings. Walmarts kinda suck and leak, at least in my experience. NAPAs are more expensive but work very well.

 

in our cars the biggest weak point is the condenser, it gets the crap kicked out of it and leaks. So if your freon leaked out its likely the condenser. I would put the new fittings on, and refill with UV dye / r134a. Also remember that converted cars need Ester oil where factory 134a cars use PAG oil.

 

Be sure that the system is totally empty of R12 before doing this.

 

Vacuuming the system down is not a necessity, but it helps. Harbor freight sells a pretty cheap vacuum pump. Also manifold gauges are your friend!

 

Changing the orphis tube should be done its like $1, and if someone used stop leak or a ac compressor went bad at some point it could be good and clogged up, which is really hard on the compressor.

[RobertISaar]

http://en.wikipedia.org/wiki/Dichlorodifluoromethane

http://en.wikipedia.org/wiki/1,1,1,2-Tetrafluoroethane_(data_page)

 

i don't know what some of that means, but there are differing ways of measuring the cooling capability from what i can tell and doesn't allow for a direct comparison...

[White93z34]

well its rather irrelevant anyhow since r12 is all but extinct, and any marginal differences are not worth the cost offset.

[Galaxie500XL]

I converted the wife's Buick Century several years ago, the compressor was shot, so I paid a local shop to do the job. The A/C does work very well, but I do notice a difference when at idle. The R-134 isn't as cold when sitting still, but is more than cold enough once the car is moving.

[WhatTheFehl]

Is this the Interdynamics kit that you would be using?

[digitaloutsider]

Take the car to a shop to get it evacuated. Some shops will pay you for the R12 they remove. You shouldn't need to change anything aside from the fittings, but I would swap out the orifice tube for good measure.

 

As it sits now, is it not cooling well or do you just want to swap it out?

[AL]

R-12 does cool better because R-12 molecules are much bigger than R-134a molecules... The bigger the molecule, the less molecules that are in the system, causing less of a cooling ability... Its weird but it made sense when explained to me... I am studying the AC system in class right now... The truth is, you dont have to replace the compressor evaporator or anything but the fittings... But the two different systems use 2 different types of oil and if any of the oil from the R-12 is in there, that will reduce the amount of refrigerant in the system... But the problem is... No shop will recharge an R-12 system as you cant legally buy R-12 any more... So you mise well go with the conversion... Have a shop evacuate the system, pull a vacuum on it, convert the system, and charge it will R-134a

[alec_b]

R-12 does cool better because R-12 molecules are much bigger than R-134a molecules... The bigger the molecule, the less molecules that are in the system, causing less of a cooling ability...

 

You contradicted yourself. You said R-12 molecules are bigger but bigger molecules cause less cooling ability... did you mean R-134a has bigger molecules?

[jman093]

You contradicted yourself. You said R-12 molecules are bigger but bigger molecules cause less cooling ability... did you mean R-134a has bigger molecules?

 

R134 molecules are much smaller than R12 molecules. This is why R134 systems are so much more leak prone that R12; the R134 molecules can slip out of the system through smaller openings.

 

Also, R12 does cool better than R134. Something about the R12 gas it aborbs and releases more heat when changing states than R134, making it more efficient. I can't explain the chemistry behind the different properties of the gases that cause this though. The size of the molecules may well be a part of the reason though.

 

As far as performance is concerned after conversion, some cars are just better than others. Some AC systems have the exchanging capacity in the condenser and evaporator that cabin cooling is not affected (but the compressor runs more). Later R12 systems, like w-bodies, are much more likely to have superior condensers and evaporators that allow for little to no performance degradation of the system after conversion. Older cars, like muscle cars and stuff, you usually will. My old g-body Monte Carlo's AC performance fell way off after conversion. I've heard instaling a smaller orifice tube will help older these systems though, and I'm hoping my electric fan conversion I want to do will help out as well by pulling more air over the condenser fins.

Edited April 21, 2010 by jman093

[99screaminregal]

thanks for all your info on this guys. the shop i'm gonna probably go with had bought a ton of r-12 before it went off the shelf.

 

the car didn't cool very well last summer and i believe it's because it probably sat forever (it's a 92 that had 72k mi on it when I got it last year).

 

i'll probably just have them do the r-12 for now and until they run out. not exactly cheap but, rather not go through the update and find leaks and replaceall those parts. although, how well does that super sealer work? that foam stuff?