The Refrigerant Revolution

The new R-1234yf refrigerant is more than just a new jumble of numbers and letters on a label. For your shop, R-1234yf means several new procedures, a certification and new equipment in order to properly handle these new systems.

The difference in handling and servicing between the R-1234yf and R-134a is flammability. Don’t be alarmed, R-1234yf isn’t extremely flammable by any stretch, but its mild flammability carries more risks and requires additional safe-handling procedures compared to R-134a.

Certification

Technicians are being recommended to recertify under the SAE standard J609 Technician Training Certification Program. This training standard has been updated with new precautions and instructions to ensure that technicians understand the handling and servicing of the new R-1234yf refrigerant. Standard J2845 also contains information concerning service and containment.

New Service

The biggest handling and servicing difference between R-1234yf and R-134a refrigerant is flammability. Using R-1234yf requires additional safe-handling procedures.

Many diagnostic procedures are the same as before, but there are additional steps that have been tacked on to account for the proper handling of the mildly flammable R-1234yf. Several of these safety checks might be automatically and semiautomatically performed by a new service machine, such as ensuring proper refrigerant type and testing the system for leaks, but they all add extra time to the overall service interval.

First, refrigerant identification must be performed with a refrigerant identifier.

Connect the identifier per manufacturer instructions and allow it to calibrate. Some identifiers will give a pass/fail grade, while others will report the percentages of chemicals within the system. Identifiers that meet the SAE specification will be calibrated to read 98% concentration as “pure.”

Prior to charging a vehicle, the machine must perform two system tests to ensure the vehicle A/C system is sealed before recharging takes place.

First, the machine will run a vacuum decay leak check. If the slope of the vacuum decay exceeds 51 mm Hg/min in five minutes, a leak is indicated, and a technician must locate and repair the leaks before the recharge can continue. In the case of a repair, remember to order the correct parts. Evaporators and other components used by R-1234yf systems are not the same as those used with R-134a.

After the vacuum test comes a partial pressurization and pressure decay leak test. The machine will instruct the technician to turn the HVAC blower motor on low, with distribution set to floor. After two minutes, a leak detector probe set for maximum sensitivity is placed in the center of a floor duct. From there, the machine charges the system with 15% of the total refrigerant in the high and low sides while the technician monitors the leak detector. If no leak is detected after five minutes, the rest of the refrigerant is charged.

R-1234yf systems use less refrigerant than older systems and are tuned to a specific amount. An undercharge will result in poor cooling or lubrication circulation, and an overcharge could cause high operating pressures and poor cooling.

New Equipment a Must

Mixing different refrigerants can cause system pressure issues, as well as other component damage and diagnostic errors.

There is no backward compatibility when it comes to refrigerants, and that goes for the recovery/recycle/recharge machines as well. In fact, by law, when a refrigerant is updated, a system’s ports must also change in size, shape and thread pattern to specifically make previous machines incompatible with the new systems and to avoid accidentally using the incorrect refrigerant. So, in order to work on these new A/C systems, you will need new equipment.

Recovery/recycle/recharge machines. New recovery/recycle/recharge machines have many upgrades that ensure the safe handling of R-1234yf and check for leakage in the system. As noted earlier, several of these safety features, such as the vacuum and pressure tests, will increase the overall service timeframe. New labeling is required on these machines that provide further instructions and cautionary statements needed for the service.

The new machines will include multiple designated fresh air intakes and strategically located ventilation drain areas if an internal release of R-1234yf occurs. Some will monitor the internal ventilation fan for a minimum of six air changes per hour and will lock out operation should this minimum flow rate fail. On-board oil injection is not allowed with the new R-1234yf equipment and must be performed using manual oil injectors.

Refrigerant identifiers. You will also need a new refrigerant identifier (some recovery machines come equipped with one). The role of the identifier in A/C service has only increased in importance with R-1234yf. Mixing refrigerants can lead to system pressure issues, component damage, diagnostic errors and environmental or personal harm.

Any new R/R/R machine must meet SAE J2843 requirements; recovery-only units must meet SAE J2851. The R/R/R unit must either come equipped with an integrated J2927-compliant refrigerant identifier, or must be capable of receiving information from a J2912-compliant identifier via a USB port.

Leak detectors. Shops servicing R-1234yf must also invest in an electronic leak detector that is SAE J2913-certified to adequately detect refrigerant leaks. New hoses, couplers and fittings that meet the J2888 standard are also required. Any dye being added to the system must be J2297-certified in order to be sure it is compatible with the refrigerant and will not harm seals or lubricants.

For salvage yards and other shops that strictly reclaim refrigerants, they must invest in a recovery-only machine that is certified to meet J2851.

R-1234yf Safety Procedure Checklist

Remember that R-1234yf is only mildly flammable. To become flammable, the mixture of air and refrigerant in a closed area like a vehicle cabin would need to be between 6.5% and 12.3% of the chemical vapor. This mixture must then experience a significant amount of energy to ignite it. In some lab tests, a spark the equivalent of a direct short at the battery didn’t ignite it. But flammability is flammability, and precautions must be taken for you, the vehicle, your customers and the environment. Below are the Specific Safety Procedures from the Mobile Air Conditioning Society’s Certification Training Manual.

» Ensure good ventilation in the work area and do not allow the refrigerant to pool in or under the vehicle, or in any low area such as a stairwell or pit. Keep car doors and windows open when charging the A/C system to prevent an accumulation of refrigerant in case of a major refrigerant leak.

» Remove ALL sources of sparks, flame or high heat from the immediate work area. This may include non-A/C-related equipment such as grinders, welders, dryers and similar equipment. Move equipment with electric motors or switches that spark internally to a safer area. Remember also that a vehicle’s ignition system can produce external sparks under some conditions – take great care to prevent arcing and accidental grounding of electrical circuits.

» Use LED work lights to prevent the risk of a broken bulb in the work area.

» Do not smoke or permit smoking anywhere in or near the work area.

» Keep well-maintained fire extinguishers in the work area and know how to use them.

» Always wear personal protective equipment during service, particularly goggles with side panels and gloves (impermeable to refrigerant). Exposure of the skin to refrigerant may result in frostbite, in which case the affected area should be rubbed with lukewarm water.

» A physician should be consulted immediately in the event of complaints following exposure to high refrigerant concentrations. Complaint symptoms may include: increased breathing rate, breathlessness, headache, accelerated pulse and dizziness.

» Do not store refrigerant tanks in low areas such as basements or stairwells, and do not transport tanks without securing them.

» If the vehicle uses hybrid or all-electric propulsion, follow the correct procedure to deactivate the high-voltage electrical system before beginning repairs.

» Prevent accidental release and exposure to refrigerant – only connect service equipment when high-side pressures have decreased, usually after the engine and compressor have been off for three minutes or more.

»Do not allow anyone under the vehicle while recharging the system. Unexpected refrigerant leakage or a sudden release of the pressure valve will pool refrigerant near the ground. Always maintain good ventilation in the work area.

» Each machine or device used to service a system with R-1234yf must be designed and approved for use with a flammable gas. Do not attempt to use equipment designed for other refrigerants on this system.

» Read the label on the vehicle and know the correct amount of refrigerant to return into the system after evacuation.

The Porsche 959 was another first to use a tire pressure monitoring system (TPMS) because it was equipped with the world’s first self-supporting run-flat tires made by Bridgestone. This TPMS setup was again used on the 928 for model years 1990 to 1994.

The early system used two sensors mounted 180 degrees apart in special holes in the valley of the wheel. The sensors looked like a stack of poker chips. A diaphragm inside the sensors connected to switches that were set to a reference pressure. The receiver was mounted on the knuckle and was an inductive coil that would pass current through the sensors. Depending on the position of the diaphragm and which switches were open or closed, the amount of current flowing through the receiver’s coil would change.