A Topped-Off R-1234yf System That Tests as a Blend

It must be recovered into a dedicated cylinder for unknown/mixed refrigerant, labeled as such, and sent to a reclaimer or to destruction.

Why neither machine can take it:

• A recovery machine's onboard cylinder is a supply vessel for that machine's refrigerant. Putting a blend into it contaminates the cylinder, the internal filter-drier, the hoses, and the seals, and every subsequent job that pulls from that cylinder inherits the contamination.
• The R-134a machine would be cross-contaminated with an A2L refrigerant; the R-1234yf machine would be contaminated with R-134a and would no longer meet the specification of the equipment's listing.
• A blend's pressure/temperature relationship does not match either pure refrigerant, so any system charged from a contaminated cylinder will be misdiagnosed forever afterward. Two identifier samples at 40/60 already prove the system is not within specification.
• Reclaimers can process mixed refrigerant; shops cannot. Recycling and reinstalling it into a vehicle is not permitted.

Use a dedicated recovery cylinder in good hydrostatic test date, evacuate the machine's hoses, and verify the cylinder is not near its fill limit by weight before starting.

Regulatory and professional points

• No venting. Knowingly venting refrigerant to the atmosphere is prohibited under the Clean Air Act's motor vehicle air conditioning provisions. Refuse the customer's vent/burn request and explain it plainly. Only a technician certified under the applicable Section 609 program may service MVAC systems, and that certification carries the recovery obligation.
• R-1234yf is an A2L (mildly flammable) refrigerant. Use only equipment listed for it, keep ignition sources away, recover in a ventilated area, and do not assume a mixed charge is non-flammable - treat an unknown blend conservatively.
• Do not reuse, resell, or reinstall the recovered mixture. Ship it to a reclaimer with the proper paperwork, or arrange destruction.
• Documentation: record the identifier make/model and calibration status, two sample results with time stamps, the recovered weight, cylinder ID and label, and the customer's authorization for the repair. Note on the repair order that the customer requested venting and was declined, with the reason.

Customer communication: the added R-134a cost them the whole charge plus a drier, and the fix is not optional - the system cannot be made to cool correctly with a blend in it.

Repair plan

1. Recover the full charge into the mixed-refrigerant cylinder; weigh it and record.
2. Inspect and repair the service ports. An adapter was forced onto a 1234yf port. Check both ports and the Schrader valves for damage or a cross-threaded adapter; replace as needed so the next technician can connect correctly.
3. Replace the receiver-drier. The desiccant in a 1234yf system is specified for that refrigerant, and the drier has been exposed to a foreign refrigerant and possible air/moisture from the top-off. Do not reuse it.
4. Address oil. Confirm the lubricant specified for this system and correct the oil charge for the replaced components per service information. Do not assume an R-134a PAG top-off is compatible.
5. Evacuate with a micron gauge to 500 microns or less, hold with the pump valved off for at least 10 minutes, and confirm the rise pattern shows neither a leak nor residual moisture.
6. Leak-check the system - the original leak that prompted the top-off was never found.
7. Charge by weight to 18.2 oz of R-1234yf using equipment listed for it, verifying the cylinder and scale.
8. Verify: performance test at a known ambient (engine at 1,500 rpm, blower high, recirc) against the service information's vent temperature and pressure targets, plus a refrigerant identifier sample post-repair confirming a pure charge.
9. Label and disclose: note the contamination event in the vehicle history so the next shop knows the system was previously blended.