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Discussion Starter · #1 · (Edited)
Disclaimer: A-L.com or myself are not responsible for any loss or damages caused by anyone attempting to perform the service described herein.

Pictures shown are of my G1 but procedures hold true for any vehicle. Please refer to your vehicle's service manual for complete specifications or PM me. I have a Complete service manual for ALL Acura vehicles from 1986 to 2002!

To successfully retrofit an R12 A/C system to operate with R134a is a pretty in-depth process but it is not beyond doing yourself for $200-$400 and can be done easily in a few hours. Stay away from the so-called do-it yourself kits you get for 30 or 40 dollars as they are just as bad as stop leak additives if not worse. When you add R134a and the proper synthetic lubricant to a system that already contains mineral oil (the proper oil for R12) what you get is a highly corrosive chemical reaction that will attack not only the o-ring seals in the system, but all the hoses too! And let me tell you A/C hoses are not cheap! So in short, although they seem to work well at first, those cheap retrofit kits are no more than a recipe for disaster! The end result is that you will spend hundreds if not thousands getting cold air again. Once this procedure is completed correctly your Air Conditioning system will be as reliable and functional as that of a new car!

Tools you will need:

-Various sized open-end or line wrenches
-Schrader valve removal/install tool
-R134a A/C Manifold Gauge Set

-Vacuum pump capable of producing 28-30 in Hg of vacuum
-Air compressor or air tank and a blow gun

Parts you will need:

- Suction and Discharge service port adaptors (get the good ones with their own Schrader valves in them.
High quality example:

Low quality examples:



-Neoprene or "HBNR" (green) O-ring master kit (available from most parts houses for approx.$15.00)
Example:


-1 quart of A/C system flushing solvent (available from most professional auto parts suppliers) Rubbing alcohol also works, but is not as effective at cleaning the system.
-New Receiver/Dryer
-6oz. of PAG 150 refrigeration oil
-R134a refrigerant (enough to fill your system to 80% of specified R12 Capacity)

Procedure:
First you will have to remove all of the old R12 refrigerant from you're A/C system. You should have this done at a facility which has the proper recovery equipment.

Next disconnect ALL of you're A/C lines and remove your old receiver/dryer. Remove the compressor from the vehicle and take it to your workbench. Remove the manifold from the compressor (This is the part that the 2 hoses connect to). Don't lose any of the old o-rings because you will need to match them to the replacements from your Master O-Ring Kit. Turn the compressor upside down to drain out as much of the old MINERAL OIL as possible. Rotating the compressor clutch will aid the process of removing oil from the unit. DO NOT ADD FLUSH SOLVENT OR FORCE AIR PRESSURE THROUGH THE UNIT AS THIS WILL RESULT IN PERMANENT DAMAGE TO THE COMPRESSOR. Leave the compressor to drain while you complete the next few steps.

Connections to Evaporator Core


Discharge hose to Condenser


G1 Receiver Dryer



Next pour some of the flush solvent into the evaporator fittings and all of the lines. Focus your flushing mainly on the condenser and evaporator as this is where most of the old oil and contaminants reside. DO NOT ATTEMPT TO FLUSH THE COMPRESSOR!! FORCING AIR OR FLUID THROUGH A COMPRESSOR WILL DESTROY IT!! Blow high pressure compressed air through the condenser, evaporator, and lines until no more oil or solvent comes out. It is very important to get as much of the old MINERAL OIL out of the system as possible. It will react with the new oil and attack the system's soft parts, i.e. seals and hoses.

Once thoroughly flushed, you can begin reassembly of your system. Reinstall the compressor on the engine. Don't add any oil to it at this time because you will only end up pouring most of it out while getting the compressor into its location on the engine. Pour 2oz. of the PAG 150 oil into the new receiver/dryer and install it in the vehicle. Pour 2 oz. of the PAG 150 oil into the discharge to condenser hose before you reconnect it. Replace each o-ring with an exact size match from your old ones. Remember that the old ones are smashed so be careful not to use too thin an o-ring replacement. Lubricate each one with PAG oil prior to installation. This will prevent cutting or tearing the o-ring as you tighten the fitting. Also don't get excited with the fittings as they can break easily, simply snug them tight and let the o-ring do its job. The compressor manifold on our Legends is comprised of 2 parts sandwiched together then bolted to the top of the compressor with 4 8mm allen bolts that use a 6mm hex key (allen wrench). This assembly is what the suction and discharge hoses connect to. There is 1 large rectangular o-ring and 4 standard round o-rings in this assembly. You can use a round o-ring of the same thickness to replace rectangular one, just be sure it fits properly in its groove. Although this seems like a pain in the ass, it's imperative to replace the o-rings in this assembly because it is a common leak point in our Legends. Pour the remaining 2oz. of PAG 150 oil into the suction side of the compressor before you reconnect the hose.

Now that you have completely flushed and resealed you're A/C system it's time to remove the Schrader valves from the service ports and install the service port adaptors. When installing the adaptors use a drop or two of red locktite on them as you will never have to remove them and you don't want them coming loose and leaking. Refer to the picture below for adaptor placement. The suction and discharge R-12 service ports are the same and R143a ones are different so be careful to properly place them. The smaller of the two with the blue cap is the suction side and the larger one with the red cap is the discharge.


Now you need to evacuate (vacuum) your system. Attach your R134a Service Manifold to the appropriate service ports and the yellow hose from the manifold to your vacuum pump. Open both valves on the manifold and turn on your vacuum pump. After a few seconds you should see the low side (blue) gauge fall into a vacuum. 25-28 in Hg is what you're looking for it to be. Once you've reached the desired vacuum, allow the vacuum pump to run for at least 30 minutes. The reason for this is to remove any noncondensable gases and all the moisture from the system. This will produce the most efficient operation of the system i.e. cooler air.

After the 30 minute evacuation process is complete you will close both valves on your R134a service manifold and turn off the vacuum pump. Look to see what the vacuum reading is and wait 20 minutes. It should not change. If it does, you have a leak somewhere that needs to be found and fixed. Double check all your connections and listen for a hissing sound while the vacuum pump is running. When you are sure there are no leaks, Make sure BOTH valves are closed on your service manifold, disconnect the yellow hose from the vacuum pump and attach it to a can of R134a refrigerant.

Start your engine and turn on the A/C. Open the LOW SIDE (BLUE) valve on your service manifold and hold the can UPSIDE DOWN until it's empty. CAUTION!! DO NOT OPEN THE HIGH SIDE (RED) VALVE ON THE MANIFOLD!! Close the LOW SIDE valve and attach another can of refrigerant and repeat this process until the system is full. CAUTION!! DO NOT OVERFILL YOU'RE A/C SYSTEM. SERIOUS DAMAGE COULD RESULT!! Most cans of R134a are 12oz.

Our G1 Legends hold 26oz of R134a and the G2's hold 24oz of R134a

Remember that "Full" is the correct amount of refrigerant for the system. System pressures will vary depending on ambient temperature and airflow through the condenser. Also, occasionally a few bubbles seen in the sight glass is NORMAL, again this can and will change due to ambient temperature and system efficiency.

Congratulations! You have successfully retrofitted you're A/C to R134a. Enjoy your cold air! If you have any questions please feel free to PM me.
 

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Hmm. My ac system stoped working years ago. I grabed a compresser from a junk yard and threw in that cheapo kragen retrofit bottle stuff. My ac has been good for about 9 months now. Do you think it is too late to do it the right way? My ac isnt that cold but i figure its because i have a lot of air and moisture in the system. I was gona have it evacuated and refilled at my shop but ive been too lazy to do it.
 

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Discussion Starter · #3 · (Edited)
Hmm. My ac system stoped working years ago. I grabed a compresser from a junk yard and threw in that cheapo kragen retrofit bottle stuff. My ac has been good for about 9 months now. Do you think it is too late to do it the right way? My ac isnt that cold but i figure its because i have a lot of air and moisture in the system. I was gona have it evacuated and refilled at my shop but ive been too lazy to do it.
You're partially right. Air and moisture are both 'noncondensable' gases which basically 'use up' space in the condenser causing the system to act as if it has a smaller condenser than it really has. Also, even though you had the system open, it is possible that some of the old R12 is still trapped in there, and there is probably also at least 6oz of mineral oil taking up space in the system. All of these issues will lead to system inefficiency as well as the destructive chemical reaction described in my DIY. If your hoses haven't started leaking yet, follow this DIY and your A/C will not only survive, but it will blow colder than you ever imagined! My '86 will blow 30 degrees when it's 100 outside.
Good Luck!
 

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Discussion Starter · #5 ·
A LITTLE MORE INSIGHT TO HOW AN A/C SYSTEM WORKS

Here is a diagram of a typical automotive a/c system:


COMPRESSOR
The compressor is responsible for compressing and transferring refrigerant gas. The A/C system is split into two sides, a high pressure side and a low pressure side; defined as discharge and suction. Since the compressor is basically a pump, it must have an intake side and a discharge side. The intake, or suction side, draws in refrigerant gas from the outlet of the evaporator. Once the refrigerant is drawn into the suction side, it is compressed and sent to the condenser, where it can then transfer the heat that is absorbed from the inside of the vehicle.

CONDENSER
The condenser is the area in which heat dissipation occurs. The condenser will have much the same appearance as the radiator in your car as the two have very similar functions. The condenser is designed to radiate heat. Condensers must have good air flow anytime the system is in operation. On our Legends, the condenser air flow is supplemented by the electric cooling fan(s). As hot compressed gasses are introduced into the top of the condenser, they are cooled off. As the gas cools, it condenses and exits the bottom of the condenser as a high pressure liquid.

RECEIVER-DRIER
The receiver-drier is used on the high side of systems that use a thermal expansion valve, as in our Legends. This type of metering valve requires liquid refrigerant. To ensure that the valve gets liquid refrigerant, a receiver is used. The primary function of the receiver-drier is to separate gas and liquid. The secondary purpose is to remove moisture and filter out contaminants. The receiver-drier has the sight glass in the top. This sight glass is often used to charge the system. Under normal operating conditions, vapor bubbles should not be visible in the sight glass. The use of the sight glass to charge the system is not recommended in R-134a systems as cloudiness and oil that has separated from the refrigerant can be mistaken for bubbles. This type of mistake can lead to a dangerous overcharged condition. There are variations of receiver-driers and several different desiccant materials are in use. Some of the moisture removing desiccants found within are not compatible with R-134a. The desiccant type is usually identified on a sticker that is affixed to the receiver-drier. Newer receiver-driers use desiccant type XH-7 and are compatible with both R-12 and R-134a refrigerants.

PRESSURE REGULATING DEVICE
Controlling the evaporator temperature is accomplished by controlling refrigerant pressure and flow into the evaporator.

THERMAL EXPANSION VALVE
The refrigerant regulator used in our Legends is the thermal expansion valve, or TXV. Commonly used on import and aftermarket systems. This type of valve can sense both temperature and pressure, and is very efficient at regulating refrigerant flow to the evaporator. This type of valve, although efficient, has some disadvantages over orifice tube systems. Like orifice tubes these valves can become clogged with debris, but also have small moving parts that may stick and malfunction due to corrosion.

EVAPORATOR
Located inside the vehicle, the evaporator serves as the heat absorption component. The evaporator provides several functions. Its primary duty is to remove heat from the inside of your vehicle. A secondary benefit is dehumidification. As warmer air travels through the aluminum fins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. Dust and pollen passing through stick to its wet surfaces and drain off to the outside. On humid days you may have seen this as water dripping from the bottom of your vehicle. Rest assured this is perfectly normal. The ideal temperature of the evaporator is 32° Fahrenheit or 0° Celsius. Refrigerant enters the bottom of the evaporator as a low pressure liquid. The warm air passing through the evaporator fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant begins to boil, it can absorb large amounts of heat. This heat is then carried off with the refrigerant to the outside of the vehicle. Several other components work in conjunction with the evaporator. As mentioned above, the ideal temperature for an evaporator coil is 32° F. Temperature and pressure regulating devices must be used to control its temperature. The pressure regulating device, in our case the TXV, functions to keep pressure in the evaporator low and keep the evaporator from freezing; A frozen evaporator coil will not absorb as much heat.
 

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Finally. Some one who does it the right way. Good show! :thumbsup:
 

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i think ill leave it up to my shop. he changed it over to 134 for me for $150, but when that didnt do it, he knocked that $150 off the price of him replacing the whole thing, which cost me another $300. so, $450 or so for a new compressor, new evaporator core, and R-134.

but great job, and i hope lots of people benefit from this.

gabe, is this going into the DIY section?
 

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Good job. A good gauge set (such as your Snap-on) goes a long way.
It is expensive though, because you need "special" equipment.

I did it all of the A/C work myself on my previous 1988 when I had access to a garage with equipment, but on my 1990, I didn't have tools nor time, so ended up taking it to a garage for A/C service.
 

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I heard you need to change the hoses too because R-134A has smaller molecues or something like that and i'll seem through the hose.
 

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:woot: great DIY Tony :bowdown: ... this will come in handy I'm sure.

Rick)Rox said:
I heard you need to change the hoses too
^^^ If the A/C system is properly evacuated then it's NOT needed, unless they're in poor shape... I didn't replace mine when I did the conversion.
 

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Discussion Starter · #12 ·
I heard you need to change the hoses too because R-134A has smaller molecues or something like that and i'll seem through the hose.
Alot of the time you do. R134a is composed of smaller molecules than R12. The hose you use is called 'barrier' hose and it has a plasticlike liner. Although, I've never had a problem with a Legend's hoses leaking R134a. I've never cut open a Legend's A/C hose, so I don't know what type they are. I can only assume beacuse so many other things about the Legend are so far advanced, maybe Acura had the insight to use barrier or some other type of hose which will contain R134a.
 

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old oil in the compressor

Nice post, nice pics, it all sounds good, but what of the old mineral oil in the compressor? If it does cause the corrosive reaction then isn't there going to be a problem? In my limited experience the compressor usually has a few ounces of oil in it. Why not remove the compressor & flush it out on the bench?

cheers, Jay
 

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Discussion Starter · #14 ·
Nice post, nice pics, it all sounds good, but what of the old mineral oil in the compressor? If it does cause the corrosive reaction then isn't there going to be a problem? In my limited experience the compressor usually has a few ounces of oil in it. Why not remove the compressor & flush it out on the bench?

cheers, Jay
Ideally you would remove the compressor, turn it upside down, and pour out as much of the oil as possible while rotating the clutch to help pump out oil, But DO NOT force any pressure through it. I have reviewed my DIY and it seems that I forgot to include that step. Although, it sure would be a pain in the @$$ to reassemble the compressor manifold with the compressor installed on the vehicle! I am fixing that immediately! Thanks for noticing and bringing to my attention!
 

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450 for replacement of everything? Sounds like not all the parts were replaced because all those parts with labor should be well over a thousand dollars easily.
 

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A/C gas

Hi Everybody,

I live in Melbourne, Australia and just though i'll pipe up on this subject.

Excellent work, Tony!

But, why would you want to convert to 134a in the first place (local pressures?)

Hydrocarbon gas (propane/butane) is closer to the boiling point of the original R12. It is much kinder to the atmosphere than 134a and it is also cheaper. Mineral compressor oil is fine as well. It also requires a lower charge weight. You don't have to change the seals either - unless there is a leak.

We have three Renault 19s. I've used Hydrocarbon (from the BBQ bottle) and it works just great. If you don't have an accurate scale then you have to be conversant with the pressures required. If not, you can/will damage the compressor if you overfill. We can buy HyChill ( a mixture of propane and butane in 300g cans) look up www.hychill.com
They sell it for $A20 to $A25.- here.

Just curios.

Cheers,

Jo
 

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team hydrocarbon explosion

Hi, I too use hc refrigerant for the reasons above. Also it's kinder to the compressor and is way less corrosive, therefore the ac system should last a long time. Duracell is the brand in Canada, ~ $17 @ Wilmar. You can go the homebrew method but it seems easier to use the premix as each can contains a known volume. Not sure about the BBQ bottle, is that straight propane? If so then the vapor pressure should be too high, which should lead to a high side pressure which is also too high and supposedly high enough to blow of the safety valve(?) on a hot day. I have heard of fearless fellows custom brewing to improve cooling (more propane) or reduce icing (more butane).
Pressure measurement does not tell you the volume, pressure is related to temperature. Unless you're controlling high side pressure by putting in a partial fill, in that case I guess as long as you do see flow thru the sight glass it should be ok as that would indicate the compressor is getting lubed.

Anyhow, do many cars down under use hc ac? Any explosions? It gives some AC guys absolute fits. The advertising here used to claim everyone in australia uses it and yet only occasionally do they get blown up. any truth to that?

BTW you should see the ridiculous duracool msd & packaging, "organic refrigerant" ,um, duh, gasoline also

hc ac is kosher in canada, but banned in some states

Jay
 

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Hi, I too use hc refrigerant for the reasons above. Also it's kinder to the compressor and is way less corrosive, therefore the ac system should last a long time. Duracell is the brand in Canada, ~ $17 @ Wilmar. You can go the homebrew method but it seems easier to use the premix as each can contains a known volume. Not sure about the BBQ bottle, is that straight propane? If so then the vapor pressure should be too high, which should lead to a high side pressure which is also too high and supposedly high enough to blow of the safety valve(?) on a hot day. I have heard of fearless fellows custom brewing to improve cooling (more propane) or reduce icing (more butane).
Pressure measurement does not tell you the volume, pressure is related to temperature. Unless you're controlling high side pressure by putting in a partial fill, in that case I guess as long as you do see flow thru the sight glass it should be ok as that would indicate the compressor is getting lubed.

Anyhow, do many cars down under use hc ac? Any explosions? It gives some AC guys absolute fits. The advertising here used to claim everyone in australia uses it and yet only occasionally do they get blown up. any truth to that?

BTW you should see the ridiculous duracool msd & packaging, "organic refrigerant" ,um, duh, gasoline also

hc ac is kosher in canada, but banned in some states

Jay
Great post/info Jay!
 

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Great post/info Jay!
Very much appreciate your feedback - Jay!

If one doesn't understand the gas charge vs pressure it is best to go by weight - for safety and avoiding damage.
BBQ gas in Australia is straight propane. I didn't put in too much but i got an extremely cold system. Your cautions are pertinent! But our hot days were only in the low 30 deg c.
Please explain, how does more butane reduce iceing?

Don't think many in Australia use HC due to brainwashing.
No explosions i'm aware of at all! If there was one it would be all over the papers etc. to the glee of dupont - no doubt?

BTW, why is HC banned in some states?

How much petrol is in a fuel tank?

I'm just blown away - the way we learn from each other!

Cheers,

Jo
 
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