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A/C Articles
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A/C Retrofitting
1. How do I know if I need to retrofit before recharging with R-134a? (How do I know if I have an R-12 system or R-134a?)
2. Can't I just recharge with R-12 refrigerant?
3. Can I just add R-134a to an R-12 system without retrofitting?
4. How do I find the low-pressure port?
5. Do I need to have the R-12 vacuumed out or can I leave some R-12 in the system?
6. Do I have to use the high side fitting?
7. Can I mix R-134a with a little remaining R12 in my system?
8. Whyuse Ester Oil instead of PAG Oil?
9. Do I need to remove the oil that's in the system? Is the old oil compatible with the new oil?
10. Do I have to change A/C system components to retrofit?
11. What's different about "High Mileage" refrigerant?
12. Why did vehicle manufacturers change from R-12 A/C systems to R-134a ?
13. When installing the service port adapters, do I have to remove the valve core from the original service port?
14. How do you actually do the retrofit with the Interdynamics kit?
15. Can I use the Retrofit Kit if I am opening the system and replacing components?
16. Does a Retrofit Kit actually work?
17. Where did the Retrofit method come from?
18. How well does R-134a work in a retrofitted R-12 system?
19. How much R-134a do you use to fill a system?
20. Are there any restrictions on the sale of R-134a Refrigerant?
21. Don't you have to flush the system?
22. Doesn't R-134a need higher pressure to work? Won't that damage my R-12 system?
23. What direction should the can be when charging – right side up or upside down?
24. How long should it take to put a can of refrigerant into an air conditioning system?
25. What about some of these "drop-in" Replacement Refrigerants for R-12 that I have heard about? Are they any good?
1. How do I know if I need to retrofit before recharging with R-134a? (How do I know if I have an R-12 system or R-134a?)
If your car is a 1994 or earlier model, you probably have an R-12 system and need to retrofit before recharging with R-134a. Check under the hood for a label indicating whether the system is R-12 or R-134a.
2. Can't I just recharge with R-12 refrigerant?
Because environmental regulations have required vehicle manufacturers to stop using R-12 systems and to use only R-134a systems, R-12 has become scarce and therefore extremely expensive. Also, R-12 can only be obtained and used for recharge by a certified mechanic. Retrofitting and recharging with R-134a refrigerant is much less expensive than recharging with R-12.
3. Can I just add R-134a to an R-12 system without retrofitting?
No. Federal Law prohibits “topping off” an R-12 system with a different refrigerant. All R-12 refrigerant must be properly evacuated before any other type of refrigerant can be added. Most mechanics will remove your old R-12 for free because they can recycle it and sell it at a profit.
4. How do I find the low-pressure port?
The low-pressure port usually has a blue or black dust cap and is located on the larger diameter metal tubing that runs between the evaporator (in the dashboard) and the compressor. To locate the low-pressure port:
1. Find the compressor.
2. Find large diameter metal tubing that leads from the compressor back to the fire wall.
3. Find port on this tube. Our quick-connect coupler should fit onto this port. To be sure, compare with the port on the other tube (smaller tube) that leads from the compressor to the condenser near the radiator. This port is larger and is the High Side port. Our quick-connect coupler will NOT fit on the High Side port.
4. Do not attempt to connect to the high side port as this can cause a can of refrigerant to explode.
5. Sometimes the low side port is on-or-near the compressor, sometimes it’s on an accumulator near the firewall…not on the large diameter metal tube.
Examples of Low-pressure (low-side) port locations
Buick LeSabre
Pontica Bonneville
Olds 88/Regency
Toyota Camry
Ford Taurus
Honda
Saturn
Mitsubishi Galant
VW Passat
5. Do I need to have the R-12 vacuumed out or can I leave some R-12 in the system?
ALL the R-12 in the system must be recovered. This must be done without venting (releasing the gas into the atmosphere) by a certified mechanic using approved R-12 Recovery equipment. Many installers will do this without charge, because the R-12 they recover from your system is valuable.
6. Do I have to use the high side fitting?
When retrofitting, it is required by law to change the adapters on the high side and low side ports. Even though you will not use the high side port during any charging procedure. At some later date, if further servicing was needed, a professional may use this port for certain procedures.
7. Can I mix R-134a with a little remaining R12 in my system?
No, the system must be evacuated first down to a vacuum measured at approx 29 inches of water.
8. Why does Interdynamics use Ester Oil instead of PAG Oil?
While both lubricants are used with R-134a, Ester is believed to be better for Retrofit systems because it is compatible with the residual mineral oil left after evacuating a R-12 system.
In addition, Ester oil is a preferred top-off oil because it is compatible with ALL PAG Oils and is much less hygroscopic, which means that it does absorb as much water from the atmosphere as PAG Oils do. This moisture can create problems in a vehicle's A/C system.
Ester is also a truly Universal lubricant which has a Single Viscosity. PAG Oils come in a variety of viscosities which must be matched to the vehicle. GM vehicles use a high viscosity (150) PAG Oil, and non-GM vehicles use a low viscosity (46) PAG Oil. You cannot use a 100 viscosity PAG Oil as a "1 size fits all" universal lubricant. Ester Oil, however, is truly universal and will lubricate properly regardless of viscosity.
9. Do I need to remove the oil that's in the system? Is the old oil compatible with the new oil?
No. The residual mineral oil left behind after you evacuate a R-12 system will not mix with the new R-134a refrigerant. That is why we add Ester Oil, because it will mix with R-134a, lubricate the system components and is compatible with the residual Mineral oil.
The mineral oil just collects in a low place in the system (such as the accumulator), where it stays, until it is removed at some later date during future maintenance or repair. The mineral oil does no good, but it does no harm either. It's just there.
10. Do I have to change A/C system components to retrofit?
In the beginning, when retrofitting vehicle air conditioning systems first came up, it was assumed that major components of the system designed for use with R-12 would have to be changed to R-134a compatible components. As more research was done, and as vehicles were actually retrofitted, the industry learned more and more about the process, namely that much less had to be done than was originally thought.
If an R-12 system is functioning properly, components do not have to be changed, and the R-12 refrigerant can be replaced with R-134a without opening up the system. If, however, the system is not functioning and repairs must be made, then the defective parts should be replaced with R-134a compatible parts.
R-134a is a smaller molecule than R-12, so R-134a hoses are designed to contain it properly. In an R-12 system, the original hoses and O-rings absorbed some of the mineral oil in the system and are coated internally with mineral oil forming a protective barrier. So, if they are not damaged, R-12 hoses and O-rings do not need to be replaced.
11. What's different about "High Mileage" refrigerant?
Interdynamics’ “High Mileage” refrigerant contains a proprietary formulation of lubricant enhancers that helps your old compressor run easier. This will make the compressor last longer and run quieter.
It contains special anti-wear and lubricant additives to restore an older A/C systems performance.
12. Why did vehicle manufacturers change from R-12 A/C systems to R-134a ?
In the mid-1990s, environmental regulations required vehicle manufacturers to stop manufacturing A/C systems that use R-12 refrigerant, which is an ozone-depleting substance (called a "CFC"), and to change to A/C systems that use R-134a refrigerant, which is NOT an ozone-depleting substance.
13. When installing the service port adapters, do I have to remove the valve core from the original service port?
Usually not.
On very few older GM models this is necessary and this is for the high side adapter only.
If your original R-12 valve cores are leaking they should be replaced after you remove all the R-12 and before you actually pull the vacuum. You can test for leakage by placing some ester oil on top of the valve core and seeing if any bubbles occur.
All ID low side port adapters fit over the existing R-12 ports and do not require the removal of the existing schrader valve core.
Most cars have high side ports that accept the ID high side port adapter that fits over the port so again, in this case, the valve core does not have to be removed.
14. How do you actually do the retrofit?
1. EVACUATE the R-12, if there is any left in the system. This must be done without venting (releasing the gas into the atmosphere) by a certified mechanic using approved R-12 Recovery equipment. Many installers will do this without charge, because the R-12 they recover from your system is valuable.
2. Attach Adaptor to the low-pressure port: [photo]The low-pressure port usually has a blue or black dust cap and is located on the larger diameter tubing that runs between the evaporator (in the dashboard) and the compressor (see question above, "How do I find the low-pressure port?"). Remove the dust cap . Attach the adapter to the low-pressure port.
3. Charge the System: [photo]Assemble the hose and refrigerant can. Be sure the engine is operating and the A/C is set to maximum cooling. Proceed to charge the system.
4. Check Pressure & Attach Label:Measure the system pressure at any time by closing the can valve. Refer to the pressure gauge chart for refrigerant level. Confirm proper pressure, disconnect charging hose, reattach blue dust cap and attach retrofit label.
15. Can I use the Retrofit Kit if I am opening the system and replacing components?
Yes, but with a couple of changes. First, if you are replacing any components of your A/C system, be sure that the replacement items are compatible with R-134a. Also check and see if flushing is recommended after installing the new component. In addition, as long as the system is open, this is a good time to remove the any remaining mineral oil.
When the system is open, you should use a POURABLE Ester Oil instead of the aerosol Oil Charge that comes with many of our kits. Pour it into the system and then, after closing the system, crank the compressor 25 times by hand to distribute the new lubricant, and then charge with R-134a to 80 to 85% of the original R-12 Capacity.
When replacing the compressor, make sure that the new compressor is compatible with R-134a, and use whatever oil the compressor recommends (PAG or Ester) in order to maintain the compressor warranty.
17. Where did the Retrofit method come from?
Described by the US Environmental Protection Agency (EPA) in a July 1996 document titled: "KEEPING YOUR CUSTOMER'S CAR COOL: SOME GUIDANCE IN RETROFITTING A/C SYSTEMS TO R-134A". The EPA refers to a "Least-Cost Aftermarket Retrofit" in which the system is not opened and there are no major component changes.
18. How well does R-134a work in a retrofitted R-12 system?
On most vehicles the air coming out the vent will be the same. On some vehicles the R-134a air will be a couple of degrees colder. On some other vehicles (rear wheel drive domestic vehicles) the duct temperature may be 2-4 degrees warmer. This is considered an insignificant amount, and based on our experience selling over 20 million retrofit kits since 1996, users are extremely satisfied with the results.
19. How much R-134a do you use to fill a system?
You fill a system with 80-85% of the original R-12 Volume. Since there are 3 oz. of R-134a used as a propellant in the Oil provided in the kit, three 12 oz. cans of R-134a should be sufficient. The amount of R-12 Refrigerant in the system can be found in the service manual or on a service plate located in the engine compartment of the vehicle.
We also provide accurate pressure gauges to make it easy to fill the system to the proper level.
20. Are there any restrictions on the sale of R-134a Refrigerant?
At the present time, there are NO FEDERAL RESTRICTIONS on the sale of R-134a Refrigerant, because it is not an Ozone Depleting Substance or "CFC". The sale of R-134a is restricted in the state of Wisconsin, where it can only be sold to certified technicians.
21. Don't you have to flush the system?
Since a functioning system is not "opened" with the Interdynamics Retrofit Kit, flushing is not necessary. 22. Doesn't R-134a need higher pressure to work? Won't that damage my R-12 system?
R-134a systems are designed to run at higher pressure than an R-12 system, which is why we use less R-134a than the amount of R-12 in the system (80-85%). This keeps the pressure at the appropriate level.
23. What direction should the can be when charging – right side up or upside down?
Plain refrigerant should be installed as a gas, with the can rightside up. If it's a can with refrigerant and oil or other additives, install as a gas by continually shaking the can during installation to prevent the other chemicals from settling to the bottom. Finish with the can upside down.
24. How long should it take to put a can of refrigerant into an air conditioning system?
It should only take a few minutes.
25. What about some of these "drop-in" Replacement Refrigerants for R-12 that I have heard about? Are they any good?
The EPA points out that only R-134a has been tested and approved by automakers for use in their vehicles, and it is also the only Replacement Refrigerant for R-12 that is widely available.
EPA adds that there is NO SUCH THING AS A "DROP-IN", since refrigerants CANNOT BE MIXED in an A/C System. In addition, ANY REPLACEMENT REFRIGERANT MUST HAVE:
* Unique Fittings for the Service Ports
* Unique Charging Devices
* Unique Label
In addition, any replacement refrigerant containing R-22 requires replacing system hoses with Barrier Hoses.
It should also be noted that some of the more talked about Replacement Refrigerants are made from up to 80% R-134a. |
A/C Recharging
1. How do I know if I need to retrofit before recharging? (How do I know if I have an R12 system or R-134a?)
2. How do I find the low-side port?
3. If I put in refrigerant (top off), do I need to add oil too? If so, what type and how much?
4. How much refrigerant should I put in?
5. Do I need to vacuum out my system before charging?
6. What does Xycleen System Cleaner do and how does it work?
7. What's different about "High Mileage" refrigerant?
1. How do I know if I need to retrofit before recharging? (How do I know if I have an R12 system or R-134a?)
If your car is a 1994 or earlier model, you probably have an R-12 system and need to retrofit before recharging with R-134a. Check under the hood for a label indicating whether the system is R-12 or R-134a.
2. How do I find the low-side port?
The low-pressure port usually has a blue or black dust cap and is located on the larger diameter metal tubing that runs between the evaporator (in the dashboard) and the compressor. To locate the low-pressure port:
1. Find the compressor.
2. Find large diameter metal tubing that leads from the compressor back to the fire wall.
3. Find port on this tube. Our quick-connect coupler should fit onto this port. To be sure, compare with the port on the other tube (smaller tube) that leads from the compressor to the condenser near the radiator. This port is larger and is the High Side port. Our quick-connect coupler will NOT fit on the High Side port.
4. Do not attempt to connect to the high side port as this can cause a can of refrigerant to explode.
5. Sometimes the low side port is on-or-near the compressor, sometimes it’s on an accumulator near the firewall…not on the large diameter metal tube.
Examples of Low-pressure (low-side) port locations
Buick LeSabre
Pontica Bonneville
Olds 88/Regency
Toyota Camry
Ford Taurus
Honda
Saturn
Mitsubishi Galant
VW Passat
3. If I put in refrigerant (top off), do I need to add oil too? If so, what type and how much?
Interdynamics’ top off products contain the proper ratio of replacement oil.
4. How much refrigerant should I put in?
We recommend using a pressure gauge for an accurate fill. Interdynamics' color-coded gauges will indicate whether you should continue filling (charging) or not. If you have just retrofitted from an R-12 system and had all the R-12 refrigerant removed, you should fill a system with R-134a at 80-85% of the original R-12 Volume. (Consult your owners manual or sticker under the hood for original R-12 volume).
5. Do I need to vacuum out my system before charging?
If the pressure gauge indicates that the A/C system pressure is lower than 10psi, air has likely entered your system, so your system should be vacuumed out.
6. What does Xycleen System Cleaner do and how does it work?
Xycleen removes sediment in the A/C system for smoother flow of refrigerant and oil and creates a cleaner, more efficient system (for better cooling). It continuously cleans, preventing the redeposit of previously removed sediment. [graph link]
7. What's different about "High Mileage" refrigerant?
Interdynamics’ “High Mileage” refrigerant contains a proprietary formulation of lubricant enhancers that helps your old compressor run easier. This will make the compressor last longer and run quieter.
It contains special anti-wear and lubricant additives to restore an older A/C systems performance. |
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A/C SYSTEM OVERVIEW  There are three primary components in a vehicle’s air conditioning system including the compressor, condenser, and evaporator. These parts are connected by tubes and hoses to form a continuous path with two distinct sections: a high-pressure side and a low-pressure side. In order to transfer heat from the vehicle’s interior to the outside air, a chemical refrigerant is circulated throughout the system. In theory, the A/C system accomplishes the same task as the engine’s cooling system, in that both absorb the heat from one area and release it to another (heat transfer). While coolant remains a liquid during the heat transfer process however, refrigerant repeatedly alternates between a liquid and a gas as it circulates throughout the air conditioning system.
THE REFRIGERANT CYCLE
The refrigerant cycle involves a three-step process that includes pressurization, condensation, and vaporization. Starting at the compressor, let’s identify these steps as we trace the flow of refrigerant through the system (See A/C System Diagrams: Orifice Tube A/C System and Expansion Valve A/C System). The refrigerant enters the compressor through the suction port as a low-pressure vapor. After squeezing this vapor into a confined area (pressurization), it is released through the compressor’s discharge port. By pressurizing the refrigerant, the compressor causes the refrigerant vapor to become much hotter than the outside air. This ensures that it will change to a liquid as the cycle enters the next phase.
Once pressurized, the compressor pumps the high-pressure refrigerant vapor to the condenser, which is located directly behind the grille in front of the radiator. As outside air is drawn over the condenser by the engine fan, or forced past it by the ram-air effect, the incoming air absorbs the heat contained in the high-pressure vapor. This causes the vapor to condense into a high-pressure liquid, completing the second phase of the process (condensation).
As the refrigerant leaves the condenser, it makes its way toward the evaporator, which is located within the air hadling case along with the blower. Before entering the evaporator, the refrigerant flows through a metering device. This results in a significant drop in pressure, allowing the refrigerant to vaporize at a lower temperature. This ensures that the refrigerant will absorb the maximum amount of heat as the blower forces warm air over the evaporator. At this point, the vaporization phase is complete, and the heat-laden vapor is drawn back into the compressor so the cycle can be repeated.
Since heat is removed from the air during the vaporization phase, the air exits the panel vents at a much lower temperature. This not only results in cool air, but dehumidified air as well. Remember, warm air has high moisture content. Consequently, when the warm air comes in contact with the cold evaporator, the moisture condenses on the evaporator surface and eventually drains onto the ground. This is why a puddle of water forms under the car after it has been shut off with the air conditioner on.
A/C SYSTEMS
Air Conditioning Component Locator Air Conditioning Component Locator
Orifice tube air conditioning systems regulate refrigerant flow to the evaporator using a fixed metering device (orifice tube).
In an expansion valve air conditioning system, refrigerant flow to the evaporator varies according to the pressure in the suction line (evaporator outlet). This is detected by a sensing bulb mounted on the line, and relayed to the expansion valve via a capillary tube.
A/C COMPONENTS
Compressor
Radial CompressorAxial CompressorThe compressor is a pump that pressurizes and circulates the refrigerant in the air conditioning system. It is mounted on the front of the engine and driven by the serpentine drive belt or its own individual belt. The compressor also serves as one of the two junctions separating the high and low sides of the system.
Condenser
CondenserSimilar to the radiator, the condenser is a large heat exchanger located directly behind the grille. As part of the system’s high side, the condenser is used liquefy the high-pressure vapor discharged from the compressor. A condenser consists of a series of tubes surrounded by thin fins, which provide a large surface area for heat dissipation. While there are various tubing arrangements used, refrigerant flow is always from top to bottom.
Evaporator
Evaporator Like the condenser, the evaporator is also a heat exchanger consisting of tubes and fins. However, that’s where the similarity ends. Unlike a condenser, which is designed to release large quantities of heat, an evaporator is used to absorb large quantities of heat. An evaporator is also much smaller than a condenser and is part of the system’s low side. Evaporators are located in the air handling case along with the blower.
Metering Devices
Metering devices are used to regulate the flow of liquid refrigerant into the evaporator. They also serve as one of the two junctions between the high and low sides of the system. There are two basic types of metering devices used in A/C systems: fixed and variable.
Orifice Tube
Orifice Tube
This is a fixed metering device located inside the liquid line between the condenser and evaporator. The orifice tube is enclosed within a plastic housing and protected by a fine mesh filter. The filter prevents debris from clogging the tube.
Expansion ValveExpansion Valve
A variable metering device that varies refrigerant flow based on cooling demand. As demand increases, the valve opens wider to permit more refrigerant into the evaporator. Once the demand has been satisfied, the valve opening is reduced to decrease flow. Cooling demand is monitored by a sensing bulb mounted on or near the evaporator.
Although there are a variety of A/C systems used in cars and light trucks, they are all generally classified according to the type of metering device they use. Consequently, an A/C system is either referred to as an orifice tube system or an expansion valve system.
Receiver Dryer or Accumulator
Receiver DryerAccumulatorDepending on the vehicle, the A/C system will either have a receiver dryer or an accumulator. Both of these components contain a desiccant, which is a chemical that attracts moisture. The desiccant serves a vital function, since the combination of water and refrigerant forms corrosive acids. Acids not only reduce A/C performance, they can ultimately destroy the system. The receiver dryer and accumulator also serve as temporary holding tanks for liquid refrigerant.
Although these two parts serve similar purposes, the receiver dryer is connected to the condenser outlet (high-pressure side) and is used exclusively in expansion valve systems. In contrast, the accumulator is attached to the evaporator outlet (low-pressure side), and is only found in orifice tube systems. The primary functional difference is that the accumulator is designed to prevent liquid refrigerant from being drawn into the compressor.
REFRIGERANT
Regardless of the type, all air conditioning systems function according to a basic law of physics that states ‘a fluid absorbs heat as it changes from a liquid to a gas, and a vapor releases heat as it changes from a gas to a liquid.’ In an A/C system, refrigerant is the transfer medium used to absorb the heat inside the passenger compartment and release it to the outside air. Refrigerant is a tasteless, odorless gas with an ability to change state rapidly within a specific temperature range. It is also oil soluble and non-corrosive. While there are scores of refrigerants on the market, there are only two types approved by vehicle manufacturers: R-12 and R-134a.
R-12, commonly referred to as Freon, has long been used as the refrigerant in all automotive A/C systems. However, R-12 contains chlorine, which is the primary cause of ozone layer damage. Consequently, legislation was passed calling for a halt in R-12 production by 1996. Long before the phase-out of R-12 began however, the automotive industry conducted extensive research and development to find an environmentally friendly alternative. They ultimately selected R-134a as the new refrigerant, and began using it in vehicles as early as 1992.
R-134a is similar to R-12, in that it absorbs, transfers, and releases heat efficiently. It is also non-flammable, and mixes well with oil, just like R-12. However, R-134a does have some unique characteristics.
* R-134a requires a special synthetic lubricant since it does not mix with mineral oil (standard R-12 lubricant).
* R-134a operates at higher discharge pressures than R-12. Therefore, systems using R-134a may not cool as well as R-12 when the vehicle is idling for extended periods (e.g. heavy traffic).
* R-134a and R-12 cannot be mixed, which is why separate equipment is needed to service vehicles using either refrigerant.
Depending on the vehicle, refrigerant capacity can range anywhere from about 28 ounces (1.75 lbs.) to as much as 64 ounces (4.00 lbs.) or more. To avoid an improper charge, always consult the manufacturer's specifications for refrigerant capacity. An improper charge will cause reduced system performance, and may even result in system damage.
REFRIGERANT OIL
In order to function properly, an A/C system requires the appropriate type and amount of oil. In addition to lubricating the compressor, refrigerant oil also maintains the operation of the expansion valve on systems so equipped. Since the oil is transported through the system by the refrigerant, it has to be compatible with the type of refrigerant being used. Mineral oil is the lubricant used for all R-12 systems, while R-134a systems use synthetic oils such as PAG (polyalkylene glycol) and POE (polyolester).
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