How to: Converting an R-12 Air Conditioner to use R-134a

[Bennett Lewison]

R134a conversion

Hello again, i didn't mean to step on any toes here. When i posted about my own inexpensive conversion from R-12 i was only relating my own personal experience with the kit. It was three years ago when i noticed my air conditioner had quit working on my 93 Ranger. I took it to the shop and explained that it had slowly lost it's cooling ability over a period of time which it had. They assumed,just as i had that it was just low on R-12 no big deal. They pumped 2 pounds more or less into the system and wholla, i had functional air once again. Cost for this was around $90.00. I made it just about six miles down the road when the air turned warm once again. Took it back and they did a leak test,found the leak and quoted me the $600.00 fix it charge. At that time it was either fix it my self or no air! It still works great after three years(knock on wood big time) I guess i must be the luckiest (s.o.b) on the planet to have regained the use of my air conditioner for less than 10% of what a professional would have charged for fixing it. Last but,not least i've read an article or two on what a contrived bunch of crap the effects of R-12 were to the enviroment. Ben

 

[Bennett Lewison]

Conversion

I just remembered something that had slipped my mind. My Nephew was an ace chevy mechanic at a large dealership. We discussed this subject in detail years ago when the conversion to R134a was just starting. In their shop they were doing a lot of conversions and they were going the whole route. They evaced the system, changed all the O-rings,pulled the compressor and tipped it upside down to get the last drop of residual oil from the R-12 out of the system. He told me the amount they got out after the evac would barely cover the end of his thumb. They concluded it wasn't worth the effort. After the inital evac they just pumped in the r134a oil and refilled with r134a period. Ben

 

[MikeP]

Chris
Outstanding writeups! Many thanks!!!
It should be noted that the Freon R12 is banned from manufacture in the United States - but the Montreal Protocol allows many countries to continue production until 2010. See the link:
http://www.china.org.cn/english/environment/62914.htm
It is my understanding that the chemical companies who manufacture Freons did and do not object to the bans on R12 because they are able to sell the other approved Freons for higher prices - hence their profits on the sales of refrigerants have increased. And the effect of the atmospheric ozone depletion on increased uv radiation at the earth's surface is true for areas like Antartica, Australia, New Zealand, southern Chile, etc. but probably not true for the United States and most of the rest of the world (ground level). And upper air measurements have shown that the depletion of the ozone layer is decreasing so it is a success story. The EPA internet web site providing information to the public on uv radiation (updated daily) is based on CALCULATED uv radiation at the earth's surface for many specific regions of the US - because the MEASURED uv radiation at the earth's surface in the US has been steadily decreasing with the years (possibly because of increased lower level air pollution including ozone). My apologies for the off-topic discussion - but it is related to all the hasstle of converting from R12 to other refrigerants in our Ford Explorers. This phasing out of R12 is a money maker for the Freon manufacturers and the air conditioning supply and repair folks - but a pain in the ____ for many of us users.
Have a good day.
Mike in a dry but cool Seattle.

 

[V8BoatBuilder]

Quasi Funcioning R134a System needs repair

Chris, and others:

My 1997 (109k miles) Mountaineer's R134a AC system *may* not be working.

Ambient Temp: 58.0 degrees F
Static System Pressure: 55psi

When I turn the dash control to "Max AC" and put the fan on high, temp all the way cool, the compressor will turn on for about 2 seconds, then shut off. The Low side pressure will dip to about 25psi, and the High side will go to around 70psi. When the compressor shuts off, both sides return to their 55psi static value. About 15 seconds later, the compressor will turn on again, and the process will repeat.

The 134a that was left in my manifold hoses was dyed bright green, similar to the color of antifreeze. Did Ford add the dye at the factory, or has a shop worked on it?

I suspect the high-side valve core is the culprit of the refrigerant discharge. When disconnecting it, there was a much larger "spurt" than when disconnecting the low side. However, I would like to not have to open the system and replace components if necessary.

My thoughts right now are to:
1) Wait for a warmer day to check the system in case it is a thermostat issue. Unlikely, since the AC system's pressure behavior.
2) Just add more 134a untill the high side pressure is somewhere in the ballpark of 2.2*ambient.

What are your thoughs? Opinions?

NOTE: I have moved this problem to a new thread:
http://www.explorerforum.com/forums/showthread.php?s=&threadid=78901

 

[Glacier991]

V8.. Your static pressure won't help us much since it would be the same almost without regard to the charge state (unless you were nearly totally out of refrigerant). Your compressor cuts out because of the low pressure switch, it's operating properly. I'd say it's pretty clear you are low on R-134. I'd add some. Also don't get all hung up on 2.2 x ambient and all that, especially at low temperatures. Add freon, watch your pressures and monitor your vents. And on colder days, you will have it cutting out a couple times a minute or more (I have to find that chart on cut out times) even when everything is just perfect.


Happy Exploring

Chris

 

[Glacier991]

Mike... thanks for the compliment. Good link on the R-12 ozone issues. One note though, the AC industry isn't really making a killing because of this. The labor prices are the same regardless of the system, 134 or R12. A jug of 134 costs about $100 (as of last summer) and a jug of R-12 costs me $750.


Happy Exploring

Chris

 

[Glacier991]

Ben... thanks for the followup. I find with my recovery equipment, if I evacuate an operating system I will usually get an amount of oil in my oil separator equal to 50-70% of system capacity (esp if I have operated it up to the point of beginning my evacuation and recovery). As for the rest, some will reside in the receiver dryer, some in the compressor, some maybe in the condensor and a bunch lining all the piping and hoses, etc I suppose. I think I mentioned in one of my posts the thinking that the old oil migrates to low points and stays put when you go to Ester in a changeover. I have no idea, but you CAN get quite a lot of oil out with the right equipment. Some of the older equipment did not separate the oil from the refrigerant, and in those cases, they were pulling it out like I am, they just didn't know it.

Happy exploring

Chris

 

[Bennett Lewison]

R-12

Just so were all on the same page. I still see R-12 for sale once in a while here in Minnesota. It's usually in the classified section of the paper. I've been told this stuff is still being blackmarketed out of Mexico. Ben

 

[Glacier991]

Ben:

You are partially correct. The actual manufacture-ban of R-12 by the signatory countries started in 1996 as I recall. However they apparently went full tilt up til then, because there is still quality (eg. DuPont, Sercon etc) virgin (e.g. not reclaimed) R-12 out there. As it gets used up the prices go up, hence the black market stuff. Most shops now check every new tank with equipment to measure purity and contamination. So for now, R-12 is around, just VERY pricey. Oh and, you need a license to buy it.

I wanted to mention another thing. The refrigerant R-134 you buy at AutoZone Pep Boys etc is the exact same stuff the pros use, chemical composition wise. Pure 134 is pure 134. Someone somwhere else on here suggested it was bad stuff and harmful to your system. THAT is hooey. I suspect someone heard an AC tech mention that there is some evidence that the "O-ring conditioners" and "leak sealers" may..MAY.. over time be detrimental, and those places do sell combined cans of 134 with those additives also. But the pure 134 is fine.

Happy Exploring

Chris

 

[Bennett Lewison]

R-12

When i say that R-12 is still being sold here in Minnesota,in the classified section of the newspaper. I'm referring to the private, used auto parts section of the paper open to all. As in no license required. Yes,i'm aware you need a license to buy R-12. You also are supposed to have a license to carry a handgun here,but there are plenty that don't follow that law either. Ben

 

[Glacier991]

On the subject of flushing... something I think is important in any conversion for everything but the compressor and evaporator... the tools for this are simple, but never discussed. I have an old flusher that uses air and like it. There are DIY knock-offs that are perfect for the DIY'er for $35 (or less). More DIY'er's should flush, so here's apost I posted elsewhere with the info on cheap flushers (air powered):

Out of curiosity I checked a good supplier with an e xcellent online link to see what their flushers are going for these days. The link is www.mvpro.com. Their flushers are only $35 and they have a special on ones with dented flush cylinders for $22. WELL within the DIY budget!!

Happy exploring

Chris

 

[MikeP]

Chris
Many thanks for the internet link which has the "Handy Dandy Flash Guns" for $34.99. Is there a writeup on the procedure and equipment flow system for doing a R134 AC system flush using this a flusher like the "Handy Dandy Flash Gun" somewhere on the internet or in your prior posts? Thanks for the continuing information on this topic.
Mike with 91 4x4 in Seattle

 

[Glacier991]

Mike...

The usual procedure is to unhook all the connections to give you access... since the system is open and you are going to replace the receiver drier/accumulator anyway (more on that below) you are already part way into it. The general idea is to blow flush through anything you can EXCEPT... the compressor (which is not a clear shot through and which could possibly be damaged) and the evaporator. Mainly this means the lines and the condensor, which is where most of the crap ends up it seems. The receiver/dryer will be new, and hence clean as a whistle <g>.

Why replace the receiver dryer some ask? Well the dessicant in this puppy holds maybe 20-30 droplets of moisture before it is saturated, and the filter material has probably done it's best work in 50,000 miles. Since you are introducing moisture into the system if it is opened, and since you are there anyway... the standard mantra is REPLACE. Not from the junkyard, btw. But new.

I have various sizes of clear plastic tubing I hook to the output end of the part being flushed... I find it easier to collect the flush that way.. I want to SEE it, and some components do not end in convenient places to recover the flush. The flush should come out clean. I REALLY really tried recently on a Ford Explorer condensor which had black death to get it clean... used everything I could think of, including MEK, just to see.. nope. When they are like that, replace em. <sigh>.

Why not evaporators? Well they are in many ways protected by the expansion valve. Not a lot can get in there. They also have in many cases a screen inlet. General practice is to let em be, but some try and do em. I don't. BUT in a black death system rebuild it's always a good idea to put a filter downstream of that item if you can. (inline add on). R-134 systems and barrier hoses present special challenges to add on filters though.

As to technique, some like to use a "Pop off "procedure, where they use their finger to plug the end of the line or component they flush and let it go in episodic intervals, "popping off" the pressure. Me, I let it run and do it over. Try both and see, you may find the other idea merit worthy. in A/C there as many ideas and many heart felt notions as anywhere. No one has the intellectual high ground. Smart people will disagree on many points.

Hope all this made sense and helps.


Happy Exploring


Chris

 

[Glacier991]

I should have added to the previous post on flushing evaporators, if you do it, REVERSE flush them. Opposite the direction of flow. It's the screen thing.

Happy Exploring

Chris

 

[Glacier991]

The subject of blended refrigerants (Hotshot, Duracool, Freezone etc) came up in another A/C thread and thought maybe this might be a good place to post this. I'd add on the issue of Duracool, many states make the use of hydrocarbon (eg falmmable) refrigerants illegal. I would also add that Frigidaire is touting it's own blend, but not for mobile A/C. Blends seem to have found a better use in home A/c and stationary refrigeration than in mobile A/C.

Blends. Let's talk about them.

There are some blends that, in my belief, in time will become accepted. A Ton (most) of em are rotten. Hey they are refrigerants and they work so what's the big deal? Well a couple of issues. First. Fractionalization.

Fractionalization - What's that?

It's the tendency for a blend to try and revert to it's component parts. The more volatile can leak away leaving the less desirable.

Next is oil miscability. Miscability is the ability of oil to dissolve in and be carried by the oil. This is how your compressor gets it's lubrication, remember? Not all refrigerant carries oil well. Some of the blends have a volatile component designed to be the carrier... hmmm if THAT leaks away... go figure THAT one out - no oil, no compressor. Others simply do a poorer job of carrying oil than 134a. And WHICH oil is always a question. Varying blends do better with differing oils.

Finally... if you use a blend, most shops do not want to fool with the system. Because they didn't do the work and want to punish you? No, because by law THEY have to reclaim the refrigerant, and a blend is VERY expensive to dispose of, they cannot reuse it. Simple as that.

Watch out for exxagerated claims on blends. If it sounds too true to be good, it is. If blends were so great why did R-12 remain the choice for so long?

food for thought...

Happy exploring.

Chris

 

[Glacier991]

OK we've opened Pandora's box on blended refrigerants, maybe more info may prove helpful to some, irritating to others, anyway....

By the time I find all my old information and post it, everyone is gonna be sick of this thread, but under the notion that too much information may be better than not enough, here's some interesting info on blends:

FRIGC or FR-12 = 39% HCFC-124+59%HRC-134a+2%butane (flammable in quantity)

Free Zone aka
RB-276 = 19% HCFC-142b+79% HFC-134a+2% syn lubricant

McCool, aka
R-406A = 55% R-22+ 41% HCFC-142b+4% isobutane
(flammable in quantity)

Autofrost, aka
Chillit, aka
GHG-X4 51% HCFC-22+28.5%HCFC-124+16.5% HCFC-142b+4% isobutane (flammable in quantity)

Hot Shot, aka
R-414b, aka
Kar Kool = 50% HCFC-22+39%HCFC-124+9.5%GCFC-142b+1.5% isobutane (flammable in quantity)

Freeze-12 20% HCFC-142b+80%HFC 134a (hmmm)

Forget the HCFC and HFC, substitute R, and HFC 134a becomes R-134a etc, which is more usual in nomenclature. The EPA has approved these blends subject to proper fittings, hoses etc.

None of these are suggested as simple "drop-in" substitutes. (eg. pump em into an R-12 system as is) I found it funny that Freeze-12 was basically R-134a anyway.

Like I said earlier time may tell the tale on blends. The issues are out there. I'd either pay to stay with R-12 or switch to R-134a before I went exploring blends. Tempting I know... but.....

Hope this helps someone...

Happy (and cool) exploring

Chris

ps. If ya JUST Gotta do a blend, my money is on RB-276
(even labeled as a Blend by the B!- or sold as Freezone - but that said, I do NOT recommend it or any blended refrigerant for the DIY'er!)

 

[Mr_Evil]

When my dad bought my Explorer in '97 the Ford Dealer had done the retrofit to R134 for which I am glad because R134 is so much easier to obtain than R12 for which my dad and I had to search high and low to find for our 4640 John Deere farm tractor. What was odd tho was that the Explorer still had its stock fittings, however, they wouldn't fit my dad's R12 equipment nor his R134a eqiupment which was a "gift" from his previous employer. There are those little quick coupler nipples you can buy from Auto Zone and screw onto your older fittings when converting. It's handier than threaded couplings.

 

[Glacier991]

VBBoatBuilder just posted a really excellent message, with accompanying photos on the subject of his repair/recharge. I HIGHLY recommend you all go look at it!

http://www.explorerforum.com/forums/showthread.php?s=&threadid=78901


Happy exploring

Chris

 

[V8BoatBuilder]

Check Your Accumulator?

http://www.imcool.com/articles/aircondition/corroded_accumulator.htm

 

[V8BoatBuilder]

Interesting A/C Info from the Ford Factory CD-ROM

The A/C clutch is controlled by the A/C cycling switch (19E561) and the A/C pressure cut-off switch, which are connected in series. The A/C cycling switch is mounted on the suction accumulator/drier (19C836), and the A/C pressure cut-off switch is mounted in the discharge line at the A/C condenser.

The A/C cycling switch closes when the pressure on the low side of the system reaches approximately 276-324 kPa (40-47 psi). The A/C cycling switch opens when the pressure drops to approximately 163-175 kPa (23.5-25.5 psi), disengaging the A/C clutch. In ambient temperatures below -1º C (30º F), the A/C cycling switch will not allow compressor operation because of low system pressures.

The A/C pressure cut-off switch is used to interrupt A/C clutch operation in the event of high system discharge pressures. The A/C pressure cut-off switch is a single-function switch that controls A/C clutch engagement. When compressor head pressures rise to approximately 2896 kPa (420 psi), the contacts open, disengaging the A/C clutch. When the pressures drop to approximately 1724 kPa (250 psi), the contacts close to allow A/C clutch operation.