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Air conditioner conversion


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04-09-02, 07:14 PM   #1  
tftranstrum
Air conditioner conversion

Have a 1990 Jeep Cherokee, 4.0L in-line 6, manual transmission; original air conditioning system (R12), wish to convert to R-134a. The old freon/R12 (what little was left) has been recoved, but not the old oil. I don't want to have to pay to have the oil evacuated.

Local auto parts store has conversion kit from Quest/EF Products that claims to have special conditioners and additives that allow the old mineral oil and the new PAG oil to be compatible. Once conditioned, the new R134a can them be added.

Anyone out there with related experience, knowledge, opinion or advice? Is it worth trying, or is the risk to the compressor and system worth the $$ to have original oil removed before installing the conversion kit?

Thanks.
tft

 
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04-09-02, 08:15 PM   #2  
Joe_F
There are no "kits" in a can. Forget those hokey 50 dollar conversion kits. They do more harm than good.

You have to remove the old oil. Most old time R12 oil is not compatible with R134A oil. They make oil now that works with the both gases.

You should call Chrysler and see what they recommend for a swap over. Then replace those parts. Newer parts are usually compatible with both R12 and R134A.

At minimum, new hoses and O rings are required. Some manufacturers recommend more.

Don't do a hokey job. You'll grenade it and it will be a waste of green backs.

I have used Autofrost in my GM cars and that's a "drop in" but isn't always very compatible with non-GM type compressors. Fords seem to puke it out (too high of a pressure for it).

 
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04-09-02, 10:22 PM   #3  
i have retrofited alot of a/c systems and do no more than fix any leaks that are present at the time and add 2 ounces of r134a approved oil and fill system with r134a to 75 to 85 percent of the r12 capacity, r134a does run at higher pressure and will damage the system if you try to fill it to full capacity, although you will want to have the system vacumed down to remove any moisture or excessive air from system before filling which will require a vacum pump and you should also have a set of r134a guages so you can read your pressure's, when you add the cost of those items alone it is usually cheaper to take it to a shop to have it retrofitted.
short of that i wouldnt spend the money on new hoses unless they was leaking already, seems like a/c is the first thing to malfunction on a vehicle even though they have been around for 30 plus years the manufactures still cannot seem to make them reliable.

 
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04-10-02, 10:51 PM   #4  
The old oil must be drained, and have the system flushed and evacuated. The oil used in R12 systems is not compatible with 134A. A 1990 Jeep will not have ester oil, and the oil in it is reported to become acidic when introduced to 134a. It will destroy your system over time. I also reccomend replacing all "o" rings, your accumulator, drier, and expansion valve. If your compressor has much wear on it, I would change it too, because the higher operating pressures of 134a will wipe out a weak compressor. I can tell you that an incomplete job will cost you more in the long run, and it's not fun having your A/C go out on you time after time. You may be much better off just repairing your leaks and going back with more R12. It doesn't seem to cause as many problems.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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04-10-02, 11:54 PM   #5  
tftranstrum
Thanks for your input...

 
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04-11-02, 05:03 AM   #6  
The reason that the oil must be changed from mineral to synthetic POE type oil is that the new refrigerants do not mix well with mineral oil and cause low oil circulation within the system. If R-134A is installed with-out an oil change, a build-up of oil in the evaperator could cause the compressor to run low on oil and either shorten it's life or cause it to blow up. The new synthetic oil and R-134A have the same flow characteristics as R-12 and mineral oil.
The reason that seals have to be changed is that synthetic oil will attack and eat rubber. All seals and o-rings usually have to be changed but most hoses already are lined and may not have to be replaced. Only the MFR knows for sure.
A drop-in replacement could be a good short term solution but there are a couple of issues you should be aware of. Most of the drop-ins are made with a small amount of "Freon" 22 which is the only CFC refrigerant still allowed to be used. This R-22 gives the system good oil flow characteristics with mineral oil. One of the problems this causes is that because the molecules of R-22 are significantly smaller than R-12, these refrigerants are more prone to leaking, especially with older unlined hoses. So although most systems will function well with drop-ins they are more prone to leaking.
One thing to be carefull of is a drop-in that is being sold that fuctions the same as R-12 and doesn't need an oil change, the only problem is that it is HIGHLY EXPLOSIVE!
It is made from a mixture of 50% propane and 50% butane!
The trade name I'm familiar with is Duracool but there are many others.


GregH.........HVAC/R Tech

 
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04-11-02, 09:57 AM   #7  
Joe_F
Greg gave you good advice. I agree.

Greg: I used Autofrost back in 1997 in my 84 Oldsmobile 88. Still in there, still blows cold. Not sure of the contents of it, but I'm always careful no matter what I use .

It is a "drop in" in the sense that all I changed was the O rings, an orifice tube and I was good to go. I know, like you said, some cars don't like it. Ford systems puke with it.

It works better with some cars than others .

Cheese: Add new hoses to your list. Many of the older hoses will cause leaks with R134A. Not to mention that over time, many of the Chrysler muffler hoses pit and rot out, turning to dust and causing leaks .

 
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04-11-02, 07:55 PM   #8  
http://www.epa.gov/ozone/title6/609/retrguid.html
if you go to the above link it may help you to decide on what all you want to do on your a/c system, retrofitting requirements can be different from one shop to the next but i will say even if you replaced every component of the a/c system which would cost 1500 plus dollars does not guarantee that your a/c system wont fail and be in need of major repairs again a year or two down the road.


Last edited by bejay; 04-11-02 at 10:17 PM.
 
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04-11-02, 07:56 PM   #9  
Yup, you're right Joe, Those steel muffler lines rotted quickly. It was a stupid idea to make them of steel when they knew the line would condensate like crazy.

Greg...When you mentioned that the synthetic oil will attack and eat the rubber, that sounds a lot like what we learned several years ago, when 134a was introduced. The similar version was that 134a, or the oil used with it (I can't remember which), mixed with mineral oil produced an acidic blend that deteriorated the system from the inside out. Is that theory still holding fast? Or is it just the synthetic oil used in 134a systems that eats away at the rubber?

I quit turning wrenches at the dodge dealer just after 134a started coming from the factory in some cars & trucks, and there were a lot of "theories" out there that surely have been adjusted by now. I remember when we all thought we would be required to convert in a few short years, and that conversion at the time meant replacing pretty much everything. Now...many manufacturers have found that most of their existing components will handle 134a, and sometimes a minimal parts changeout is all that is required.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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04-12-02, 08:04 AM   #10  
cheese:
As far as I know the mixing of mineral oil and polyol oil (called PAG oil in automotive I believe) will not cause decomposition.
The creation of acids is normally from excess moisture in the system combining with the chlorine atoms in R-12 and breaking down under the heat of excess head pressure. The result of this breakdown is hydroflouric and hydrochloric acid.
In commercial refrigeration circles, whenever a refrigeration system is converted from a CFC refrigerant to a non-CFC one, the main concern is removal of the mineral oil. The reason for the removal is as stated before. Non CFC refrigerants have no affinity for each-other and the oil will not properly circulate. Under some circumstances it is possible to have 25% of the system's oil elsewhere in the system.
In commercial refrigeration the standard that is normally used is to have less than 5% mineral oil to POE oil before making a conversion, which would take about three complete oil changes. Not because of a reaction but to ensure that mineral oil does not lay in the evaperator coil. The effect this has is if the mineral oil remains sitting in the evaperator coil, the oil will insulate the portion of coil it sits in, making for an inefficient system.
This is why you can install R-134A in a system with-out an oil change and have it appear to work just fine. The problem is with what you can't see. This could cause a reduction in cooling capacity or in extreme cases, a loss of lubrication in the compressor.
This is where drop-in blends come in .
The ones I am familiar with use "Freon" 22 in the mix to allow the refrigerant to carry the oil back to the compressor.
Hoses:
Not that long ago autmotive refrigerant hoses were not lined but made of a solid but permeable rubber. The R-12 molecules were of a size that would not allow them to readily pass through. Although the weeping was small, a 1/4 ounce of R-12 per year was considered normal. This can be seen in older hoses by looking at the surface of the hose. Normally there will be visible pin pricks in the hose. This is to allow the seeping refrigerant to pass through through the outer skin of the hose with-out causing the surface to bubble.

Make sense?


GregH.........HVAC/R Tech

 
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04-12-02, 09:01 AM   #11  
Joe_F
Yup. I believe the new hoses are now called barrier hoses as a result.

Most replacement parts work with both R12 and R134A.

I like to stick with what came in it originally, but if properly converted, R134A is ok. It is less efficient as a refrigerant than R12 is.

In hotter areas of the country you might notice a difference, but in most you probably wont.

 
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04-12-02, 03:47 PM   #12  
rickwhoo
i have used about 25 of those r134 kits costing me 30 bucks. every one works great. one car was a 89 ford bronco II that whenever i charged it with r-12, it leaked out within 2 weeks. used conversion kit 4 years ago and still blowing cold.

 
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04-12-02, 04:51 PM   #13  
I've converted two Toyotas, One Chevrolet (Dual Air) and one Pontiac to 134. On all I removed the compressor and poured out the oil into a measuring cup. Went back with correct oil for 134 (ester or PAG) flush system while compressor was out, changed dryer and went back with 134. I did the first conversion over 5 years ago and have not had any problems.

 
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04-13-02, 02:03 AM   #14  
Now my luck seems to go the other way with the conversions. My Oldsmobile delta 88...converted to 134a and trashed 3 compressors, 2 within about a month of each other. My Chevy scottsdale converted to 134a, after about 2 yrs had compressor failure. Now whether this is due to the higher pressures of 134a, or just the quality of the compressor, I don't know. I did drain the oil, flush the system, changed orfice, seals, and accumulator/drier, vacuum and fill with guages to proper pressures. Maybe just bum luck. I converted several at the shop and never had a comeback on any.

Thanks Greg...for the info!


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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04-13-02, 07:14 AM   #15  
cheese:
I had to laugh when I read your statement "Now my luck seems to go the other way with the conversions."
This reminds me of why I have been hanging around here lately.....to get information to help me with my latest project, an "89 full size van, 6.2 diesel to carburated 350 conversion.
I've been trying to do this project by the book, but the" luck " I've been having is more attributable to stupid mistakes. Forgetting to tighten a couple of intake bolts and filling crankcase with anti- freeze, not bothering to fully check out a "perfectly good" 350 from my old crew cab and discovering later a bad head and leaving the keys in the ignition for just a second and having someone drive away in it.

The point of this story is to illustrate that sometimes having more knowlege about a subject can change our "luck".

This article is written for the commercial HVAC/R trade but the principles still apply.

http://www.contractormag.com/articles/0799/chvacr.asp

tftranstrum: Sorry for this rambling and I hope your question is being answered.


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04-13-02, 08:44 AM   #16  
tftranstrum
Is my question being answered?

I think so...it's good reading and I'm learning a lot. Certainly a wealth of knowledge and varied experience out there.

However, from these postings and the recommended links/reading, it seems that even with experience, knowledge, money, and the proper equipment and parts, retrofitting the a/c system is a gamble at best.

And from Wheeler's article (the 'hvacr authority'), it seems that even the very best trained and intentioned service techs with their knowledge and equipment don't do a proper job. So I'm not even confident that going to a Chrylser/Jeep dealer and paying top dollar ensures it will be done right, or last very long without failure.

So...may just endure another summer without a/c and spend the cash on something nice for my sweetheart...much better gamble!

 
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04-13-02, 09:21 AM   #17  
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As others have said, "theories" have been "adjusted".

It is safe to say that sticking with what came with the car is the way to go. It might be more costly to put in R12, but the fact is, if it came R12 originally, that's the way to go .

As for substitutes, they vary in quality. I have used the Autofrost with good success. Then again, GM has a very good system to start with, so good, other car makers (like Rolls Royce) use it .

If you had a dealer convert it, and it went bad on you, you have recourse. The same with a shop. You will have a gurantee (or should).

If you can live without it, that's cool too. All depends. I like to have it . The system in my Olds is so good, that it had the ORIGINAL A/C charge until 1997 when I serviced it. That's pretty good .

 
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04-13-02, 10:26 PM   #18  
I tend to agree that if you had R12 originally, you probably will be better off going back with it. I decided not to retrofit my park avenue, and haven't had my infamous compressor failure yet. I just charged with R12 and left it alone. The drawback is that you need a certification # to buy R12. I have an ASE #, but the average DIYer wouldn't have the need to go to this extent. You could make the repairs needed and have a shop charge it for you.


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04-14-02, 07:44 AM   #19  
Joe_F
Yes, that is correct Cheese.

However, it may be CHEAPER to fix the problem at hand than to covert it all the way around to something it wasn't designed for.

Most parts today will work with either R12 or R134A. I have had good luck with Autofrost. I know it was on the EPA's "OK"list some time ago.

Maybe Greg has more information on it. I used it that summer because my neighbor had it in his shop. I remember the day we did the repair. It was brutal out. I was very happy coming home with ice cold fogged windows that night

 
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04-14-02, 07:32 PM   #20  
Here is a site that has some current info on refrigerants. The automotive replacements are on the bottom of the page.

http://www.refrigerant-supply.com/r-12.htm

It's been a while since I looked at a list like this and find it interesting that most of the replacements have HCFC's in the blend. HCFC refrigerants like R-22, are the type that is used in most central A/C's, and are for now still available. The problem is that these will soon go the way of R-12.
In commercial refrigeration the choice of which replacement refrigerant to use is much simpler. We pretty much have to use a replacement that is approved by the compressor manufacturer.
They are the ones to test each refrigerant and decide which ones will give their units a long service life. Compressors that I work on range in price from $500.00 for ones found on a small pop cooler to $7500.00 and up for ones found on supermarket rack systems. I can't afford to experiment on my customer's equipment.
I asked my auto parts man last summer about alternative refrigerants for automotive. He told me that they don't carry anything other than 134a because their compressor supplier won't warranty their units on anything other than that refrigerant.

I've seen a lot of the advertising hype that makers of these so called wonder refrigerants put out. One only has to read a competitor's literature to find out what problems there are with it.
I think Joe_F and cheese agree that nothing will ever work as good as the refrigerant that the system was designed for.

Joe_F, you mentioned that the quality of the GM system was why you havn't had any problems with autofrost. This is probably close to being quite true. Not so much that GM is superior to other systems, but rather that the system is in good condition and properly maintained.


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04-14-02, 08:31 PM   #21  
Joe_F
Greg:

The A6 axial GM compressor (often affectionately called the "log" because of what it looks like) is one stout and strong unit. Almost every manufacturer has borrowed this from GM. I believe it was originally a Frigidaire design when GM owned them. That's why you'll see GM/Frigidaire on some older GM car compressors.

They are absolute champs at snow. I have one in my 79 T/A. Haven't touched the system since 99 when I got the car and I suspect it hasn't seen service in a long time. It might be the original charge for all I know. It snows like a champ in there. Who needs it with T-tops ?

That being said the R4 is pretty good too (often called the "pancake") . I run the system every so often in the winter so things don't seize up come time to use it. Running the defroster helps as it cycles the compressor. My 84 Olds has the R4 radial compessor.

My experience is that old GM's like mine take well to Autofrost. I would like to stay with R12, but it's up to about a grand for a 30 lb thingie.

I can remember buying those at the parts store back in the late 80's for about 100 bucks or less a thing! R12 cans were sold in stores and were about 2 bucks on sale! Lol.

 
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