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R12 to R134a Conversion


GM-MAN

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Hi, I was told of this forum by a fellow member at Cadillacowners.com for an A/C question that's pretty much self explanatory from the title.

I am a reefer mechanic and know my way around refrigeration systems but I've never converted one before so I'm not sure what I have to keep in mind if I want to introduce R134a in my R12 79 ElDorado.

Here are my questions:

1 - Where does the oil from the compressor drain and fill? Through the suction and discharge ports?

2 - How important is it to replace the receiver tank?

3 - The compressor on the car has two plugs, one for power and the other I don't know. Is it for the climate control?

4 - Should I just forget this conversion and just put in the propane-based R12b that is available as an R12 substitute?

5 - Anything else I should keep in mind about doing this conversion?

Thanks in adavance to anyone that may be able to help!!!!!

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Hi, I was told of this forum by a fellow member at Cadillacowners.com for an A/C question that's pretty much self explanatory from the title.

I am a reefer mechanic and know my way around refrigeration systems but I've never converted one before so I'm not sure what I have to keep in mind if I want to introduce R134a in my R12 79 ElDorado.

Here are my questions:

1 - Where does the oil from the compressor drain and fill? Through the suction and discharge ports?

2 - How important is it to replace the receiver tank?

3 - The compressor on the car has two plugs, one for power and the other I don't know. Is it for the climate control?

4 - Should I just forget this conversion and just put in the propane-based R12b that is available as an R12 substitute?

5 - Anything else I should keep in mind about doing this conversion?

Thanks in adavance to anyone that may be able to help!!!!!

What is the reason for the desire to convert to R-134a? It may just need a booster charge of R-12 to restore it to peak performance. If there is a leak with R-12, then R-134a will leak out at a much faster rate due to the smaller size of the R-134a molecules. The rubber portion of the hoses may not be compatable with R-134a so the hoses may need to be rebuilt/replaced with barrier type hose. That being said, the first step is to repair the leak.

The accumulator will need to be replaced as the dessicant in the original accumulator will not be compatable with R-134a. You will need to remove the compressor and drain the old oil out of the suction and discharge ports. You will also need to disconnect the lines at the condenser, evaporator and accumulator. Use a flush gun to flush as much of the mineral oil from the system. Do not attempt to flush a line that has a muffler (looks like a mini accumulator) in it - replace the line. Flush the evaporator, condenser (the old style serpentine condensers flush out just fine). Replace the orifice tube as you need to remove it to flush the condenser.

Replace all the o-rings at the connections and lube them with 525 viscosity mineral oil or Nylog - an o-ring lubricant.

Flush the compressor with PAG-150 oil - keeping track of the amount you add to the suction port while rotating the clutch. When clean PAG oil comes out, you can install the new compressor. Since you know how much PAG oil you added to the compressor, add the balance of a full charge to the new accumulator and reconnect all of the lines. Turn the clutch a few turns by hand to make sure no oil will slug the compressor.

Install R-134a port adapters - make sure to use high quality brass fittings - not the cheapo aluminum fittings. Install the retrofit label near the accumulator.

Evacuate the system with a vacuum pump - it is best to use a micron gage to evaluate how much moisture is in the system but if you let the pump run for 2-3 hours, you should be fine. Provided the system holds vacuum for at least 1 hour, charge in the same amount of R-134a as what is specified for R-12.

Cars with clutch fans usually do not cool well with R-134a....You may need to replace the clutch. That sums up the proper method to convert the car to R-134a....as you can see it is a hell of a lot of work and you will notice a 5-7 degree INCREASE in vent temperatures at idle.

I would recommend that you keep the car R-12. Most A/C shops still have R-12 and it is still available (you do need a 609 card to buy it though).

What is R-12b????

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Lost of good Points of view here Link...

I echo KHE, why are we doing this?

1) If its to save the environment...<Buzz> sorry R134a also is bad for the ozon

2) If its to save money... <Buzz> sorry R134a is also in short suppy and is not cheap

3) If its to make the A/C colder... <Buzz> sorry Retro fitted system are only about 60% as cold as original R12 systems... If you live anywhere other than Seatle you will be running your system on Max all of the time...

Looks like an Oh for Three project to me...

caddy.jpg

Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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Anyone ever tried this stuff?

http://autorefrigerants.com/co00033.htm

I Have a VERY slow leak (need a half a can or so once a year). And this Enviro-Safe stuff has worked for me.. I have always just added to what's in there, haven't needed to take out the old freon. Blows nice and cold. I have never actually ordered from this site, it's just the first thing that came up whaen I googled that brand freon replacement.

this stuff will work withy both R-12 and 134a, although I have only used it in my R-12 system on my 92 eldo.

-dave B)

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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Anyone ever tried this stuff?

http://autorefrigerants.com/co00033.htm

I Have a VERY slow leak (need a half a can or so once a year). And this Enviro-Safe stuff has worked for me.. I have always just added to what's in there, haven't needed to take out the old freon. Blows nice and cold. I have never actually ordered from this site, it's just the first thing that came up whaen I googled that brand freon replacement.

this stuff will work withy both R-12 and 134a, although I have only used it in my R-12 system on my 92 eldo.

-dave B)

You really aren't supposed to mix refrigerants with R-12. There are some good R-12 substitutes available - Autofrost (R-406a) is a good one but because it is a blend of three refrigerants, it requires a leak free system.

In GM-MAN's case, to properly convert the car to R-134a will cost much more money than fixing the leak and recharging with R-12.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Most of these "hydrocarbon" based substitutes are based on Propane and similar molecules. Propane makes for an awesome coolant, even better than R12 (just put your hand on the side of a propane tank while your BBQ is doing its thing)... Propane also wins in the fact that unlike R12 and R134a it has ZERO impact on the ozone layer...

On the other hand however... if your system has (or developes) a leak and the propane manages to pool up somewhere under your hood... You can get the dreaded "KA-BOOM" effect...

caddy.jpg

Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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What is the reason for the desire to convert to R-134a?  It may just need a booster charge of R-12 to restore it to peak performance.  If there is a leak with R-12, then R-134a will leak out at a much faster rate due to the smaller size of the R-134a molecules.  The rubber portion of the hoses may not be compatable with R-134a so the hoses may need to be rebuilt/replaced with barrier type hose.  That being said, the first step is to repair the leak.

The accumulator will need to be replaced as the dessicant in the original accumulator will not be compatable with R-134a.  You will need to remove the compressor and drain the old oil out of the suction and discharge ports.  You will also need to disconnect the lines at the condenser, evaporator and accumulator.  Use a flush gun to flush as much of the mineral oil from the system.  Do not attempt to flush a line that has a muffler (looks like a mini accumulator) in it - replace the line.  Flush the evaporator, condenser (the old style serpentine condensers flush out just fine).  Replace the orifice tube as you need to remove it to flush the condenser.

Replace all the o-rings at the connections and lube them with 525 viscosity mineral oil or Nylog - an o-ring lubricant.

Flush the compressor with PAG-150 oil - keeping track of the amount you add to the suction port while rotating the clutch.  When clean PAG oil comes out, you can install the new compressor.  Since you know how much PAG oil you added to the compressor, add the balance of a full charge to the new accumulator and reconnect all of the lines.  Turn the clutch a few turns by hand to make sure no oil will slug the compressor.

Install R-134a port adapters - make sure to use high quality brass fittings - not the cheapo aluminum fittings.  Install the retrofit label near the accumulator.

Evacuate the system with a vacuum pump - it is best to use a micron gage to evaluate how much moisture is in the system but if you let the pump run for 2-3 hours, you should be fine.  Provided the system holds vacuum for at least 1 hour, charge in the same amount of R-134a as what is specified for R-12.

Cars with clutch fans usually do not cool well with R-134a....You may need to replace the clutch.  That sums up the proper method to convert the car to R-134a....as you can see it is a hell of a lot of work and you will notice a 5-7 degree INCREASE in vent temperatures at idle.

I would recommend that you keep the car R-12.  Most A/C shops still have R-12 and it is still available (you do need a 609 card to buy it though).

What is R-12b????

Thanks for answering, as Ranger suggested you might be the most knowledgeable here who could.

I also own an 85 Buick LeSabre CE with R12 and still has it's charge. I have no desire to change over to R134a as I know its a lesser freon.

Thing is, its impossible to find someone with R12 as its illegal here north of the border. Since my shop stocks all current freons (mainly R134a, R22 and R404a), I can get it at cost, especially since a full cylinder of R134a would cost me here $193 CDN.

Since I cannot get R12 here (I would gladly overpay for even half a cylinder), Ièm left with little choice. R12b, the propane based substitute, was suggested to me by a fellow mechanic as he also said it would be far easier than the conversion, is an alternative but I find R134a to be a much easier solution to me mainly since we stock tons of it at work. The oil is also no problems nor are the replacement o-rings. The accumulator though (which I assume is the longer of the two cylinders with a port connection) would be something I would have to buy elsewhere I guess.

Of course, If I repair whatever leaks I find I could always drive to Buffalo and see if I could get it charged with R12 there. I do have my ODP card which allows me to buy freon but its only valid in Ontario.

Please dont missunderstand, I dont want to use R134a, I just find that itès so much easier for me. My Eldo is a 79 and I bought it only a month ago. I found the old compressor with the clutch seized and the belt off. Lord knows how long its been without A/C. I installed the compressor from my 84 Cutlass Supreme, as I only use it as a parts car, since the clutch was fine.

Im only trying to first find out if the A/C system is repairable, after that I`ll see about charging it.

I just thought that a conversion was probably a little easier is all.

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On the other hand however...  if your system has (or developes) a leak and the propane manages to pool up somewhere under your hood... You can get the dreaded "KA-BOOM" effect...

has there ever actually been a documented case of this? Not trying to start an agument, but it seems like if this was a problem, they wouldn't be able to sell the stuff, just curious, thats all. :)

-dave B)

P.S. Why are you not supposed to mix it?

Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k

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GM-MAN,

Is R-12 actually illegal in Canada or do you need to be certified to purchase it? I recall OnyxSTS stating that the laws vary from province to province. In the US, R-12 cannot be manufactured but it can be used and sold. In order to buy R-12, you need an EPA 609 card. Most A/C shops stock R-12 and R-134a.

Since you are going to install a used compressor, I would recommend replacing the shaft seal to be on the safe side. It would also be a good idea to replace the accumulator since it is 26 years old. Once you have the system repaired, you can evacuate the system with a vacuum pump and charge a small amount of R-22 into the system and then go over everything with an electronic leak detector to assure there are no leaks. Recover the R-22 and then drive to a border town in the US and have the system charged with R-12....

Another alternative would be to use Autofrost (R-406a). It is a blend of three refrigerants and as such requires a leak free system. I have use Autofrost for almost 4 years now in my '86 Park Avenue and it works great. You need to make sure that you have barrier hoses prior to using it or it will leak out through the hoses.

davedog:

The EPA states that it is illegal to mix refrigerants.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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On the other hand however...  if your system has (or developes) a leak and the propane manages to pool up somewhere under your hood... You can get the dreaded "KA-BOOM" effect...

has there ever actually been a documented case of this?

No, not that I'm aware of...

Wouldn't want to be the first though...

caddy.jpg

Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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Anyone ever tried this stuff?

http://autorefrigerants.com/co00033.htm

I Have a VERY slow leak (need a half a can or so once a year). And this Enviro-Safe stuff has worked for me.. I have always just added to what's in there, haven't needed to take out the old freon. Blows nice and cold. I have never actually ordered from this site, it's just the first thing that came up whaen I googled that brand freon replacement.

this stuff will work withy both R-12 and 134a, although I have only used it in my R-12 system on my 92 eldo.

-dave B)

You really aren't supposed to mix refrigerants with R-12. There are some good R-12 substitutes available - Autofrost (R-406a) is a good one but because it is a blend of three refrigerants, it requires a leak free system.

In GM-MAN's case, to properly convert the car to R-134a will cost much more money than fixing the leak and recharging with R-12.

Well, I disagree. If he has had a leak bad enough to cause a cooling failure, he will have moister in his accumulater/drier and it should be replaced, same as if you convert. The orifice tube often needs replacing, even if a system has never been opened due to small contaminates, same as if he converted. If you're opening the system anyway, why not change the o rings, I would, same as if he converted. If he has a leak, the system should be evacuated and pressure tested, as I said earlier, same as if he converted. Now he might need a new pressure switch, (I haven't looked at the Caddy system to find out), that and the r-134 would still be cheaper than 'properly' repairing his current system with r-12. Now if he's happy to just get by and hope it doesn't break on a 100 degree day, then add a substitute and ride!

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GM-MAN,

Is R-12 actually illegal in Canada or do you need to be certified to purchase it? I recall OnyxSTS stating that the laws vary from province to province. In the US, R-12 cannot be manufactured but it can be used and sold. In order to buy R-12, you need an EPA 609 card. Most A/C shops stock R-12 and R-134a.

Since you are going to install a used compressor, I would recommend replacing the shaft seal to be on the safe side. It would also be a good idea to replace the accumulator since it is 26 years old. Once you have the system repaired, you can evacuate the system with a vacuum pump and charge a small amount of R-22 into the system and then go over everything with an electronic leak detector to assure there are no leaks. Recover the R-22 and then drive to a border town in the US and have the system charged with R-12....

Another alternative would be to use Autofrost (R-406a). It is a blend of three refrigerants and as such requires a leak free system. I have use Autofrost for almost 4 years now in my '86 Park Avenue and it works great. You need to make sure that you have barrier hoses prior to using it or it will leak out through the hoses.

davedog:

The EPA states that it is illegal to mix refrigerants.

Yes, it is illegal to charge or sell R12. Regardless of any inventory. I am certified to buy freon (here it's called an ODP card and is only valid in Ontario) but not R12.

Otherwise, you're suggestions are quite valid and I will replace the accumulator. I just hope the hoses themselves can hold pressure. The fittings can leak as the o-rings are replaceable but I'd like to avoid replacing the rubber if at all possible.

Yes, the front seal is a good idea to replace, as it will give me the opportunity to properly inspect the clutch. It does turn and freely so that's a good sign.

Do I have to order the accumulator through GM or do they make aftermarket versions I could purchase at any hardare store?

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GM-MAN,

Is R-12 actually illegal in Canada or do you need to be certified to purchase it?  I recall OnyxSTS stating that the laws vary from province to province.  In the US, R-12 cannot be manufactured but it can be used and sold.  In order to buy R-12, you need an EPA 609 card.  Most A/C shops stock R-12 and R-134a.

Since you are going to install a used compressor, I would recommend replacing the shaft seal to be on the safe side.  It would also be a good idea to replace the accumulator since it is 26 years old.  Once you have the system repaired, you can evacuate the system with a vacuum pump and charge a small amount of R-22 into the system and then go over everything with an electronic leak detector to assure there are no leaks.  Recover the R-22 and then drive to a border town in the US and have the system charged with R-12....

Another alternative would be to use Autofrost (R-406a).  It is a blend of three refrigerants and as such requires a leak free system.  I have use Autofrost for almost 4 years now in my '86 Park Avenue and it works great.  You need to make sure that you have barrier hoses prior to using it or it will leak out through the hoses.

davedog:

The EPA states that it is illegal to mix refrigerants.

Yes, it is illegal to charge or sell R12. Regardless of any inventory. I am certified to buy freon (here it's called an ODP card and is only valid in Ontario) but not R12.

Otherwise, you're suggestions are quite valid and I will replace the accumulator. I just hope the hoses themselves can hold pressure. The fittings can leak as the o-rings are replaceable but I'd like to avoid replacing the rubber if at all possible.

Yes, the front seal is a good idea to replace, as it will give me the opportunity to properly inspect the clutch. It does turn and freely so that's a good sign.

Do I have to order the accumulator through GM or do they make aftermarket versions I could purchase at any hardare store?

You can buy a new accumulator at any auto parts store. If the hoses leak, you can have them repaired for a lot less money than new ones (if new ones are still available).

Can you buy Autofrost in Canada?

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Anyone ever tried this stuff?

http://autorefrigerants.com/co00033.htm

I Have a VERY slow leak (need a half a can or so once a year). And this Enviro-Safe stuff has worked for me.. I have always just added to what's in there, haven't needed to take out the old freon. Blows nice and cold. I have never actually ordered from this site, it's just the first thing that came up whaen I googled that brand freon replacement.

this stuff will work withy both R-12 and 134a, although I have only used it in my R-12 system on my 92 eldo.

-dave B)

You really aren't supposed to mix refrigerants with R-12. There are some good R-12 substitutes available - Autofrost (R-406a) is a good one but because it is a blend of three refrigerants, it requires a leak free system.

In GM-MAN's case, to properly convert the car to R-134a will cost much more money than fixing the leak and recharging with R-12.

Well, I disagree. If he has had a leak bad enough to cause a cooling failure, he will have moister in his accumulater/drier and it should be replaced, same as if you convert. The orifice tube often needs replacing, even if a system has never been opened due to small contaminates, same as if he converted. If you're opening the system anyway, why not change the o rings, I would, same as if he converted. If he has a leak, the system should be evacuated and pressure tested, as I said earlier, same as if he converted. Now he might need a new pressure switch, (I haven't looked at the Caddy system to find out), that and the r-134 would still be cheaper than 'properly' repairing his current system with r-12. Now if he's happy to just get by and hope it doesn't break on a 100 degree day, then add a substitute and ride!

Randy,

I am not sure what you disagree about? When I refer to "mixing refrigerants" I mean adding one type of refrigerant to a system that contains another type. An example would be a system that has a partial charge of R-12 and someone tops it off with R-134a. That is illegal according to the EPA section 609....you must apply unique fittings to the high and low side ports and affix a label stating the system has been converted.

Many people think that a conversion from R-12 to R-134a will miraculously cure the root cause of the leaking system....R-134a will leak out faster in a leaky system as the R-134a molecules are smaller than R-12. Since the leak should be repaired anyway as not to keep venting refrigerant to the atmosphere, the vehicle owner needs to make a chouce on wether he wants to spend the extra money to properly convert the system to R-134a.

I am not against converting a car to R-134a but many older cars with clutch fans, non-barrier hoses, and serpentine condensers do not cool anywhere near as well as they did with R-12. Also, a simple leak is often fixed easily and recharged with R-12 for less money than a conversion to R-134a.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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To start with I didn't say a thing about mixing refrigerants! I'm talking about the cost to convert to r ;) 134 vs the cost to 'properly' repair and recharge with r12! If he repairs and replaces all he should and recharges with r12, he will spend as much or more than with r134. Once converted he will be able to get it serviced anywhere.

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To start with I didn't say a thing about mixing refrigerants! I'm talking about the cost to convert to r ;) 134 vs the cost to 'properly' repair and recharge with r12! If he repairs and replaces all he should and recharges with r12, he will spend as much or more than with r134. Once converted he will be able to get it serviced anywhere.

True - the car can then be serviced anywhere once it has been converted to R-134a. But to properly convert a 1979 model, the entire system needs to be flushed to remove the old R-12 mineral oil from the system. There is a lot of labor involved there. Any mineral oil left in the system will reduce the cooling capacity when converted to R-134a.

If the vehicle owner can accept a vent temperature increase of 7-10 degrees, fine but don't expect a 26 year old car to cool as well on R-134a as it did with R-12.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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