Split System Retrofit with Mixed Refrigerant and No Paperwork

The technician cannot simply add gas. First, the system contains a refrigerant of uncertain composition: the 'MO99 top-up' sticker indicates an R-22 replacement blend was added to an R-22 system, so the cylinder now holds a mixture. Under the Refrigerant Handling Licence obligations, refrigerant must be recovered, not vented, and a mixed or unknown refrigerant cannot be identified for reuse. Second, the technician must not add virgin R-22 or another blend on top of an unknown mixture, because fractionation and composition changes make performance and safety unpredictable. Third, the leak that caused the low charge must be located and repaired before any recharge, since recharging a leaking system is a false economy and may breach the no-venting and leak-management expectations of the licence. The correct sequence is: isolate and recover the existing charge into a dedicated recovery cylinder labelled as mixed/unknown, pressure-test with OFN to find the leak, repair, evacuate, then decide with the customer whether to retrofit properly to a compatible refrigerant or replace the unit. The afternoon schedule is irrelevant to these obligations.

A single hose set used for R-22 then for a different refrigerant will carry residual oil and refrigerant, contaminating the next system and the recovery cylinder. Because the existing charge is already an unknown mixture, the technician should dedicate that cylinder and ideally that hose set to 'unknown/mixed' service. Practical steps: recover the unknown charge first into a cylinder clearly labelled with the date, the system, and 'mixed/unknown - do not reuse'; then purge the hoses and recovery machine with nitrogen and draw a vacuum on the machine before any subsequent job. If a second refrigerant (for example an HFC retrofit) is to be charged later, use a separate hose set or thoroughly evacuate and purge between uses. The technician should also check that the recovery cylinder is within its test date and is not overfilled, weighing the recovered amount against the cylinder's marked capacity. Documenting the recovered weight and the cylinder identity protects both the technician and the customer.

The technician should explain that adding gas to a leaking, mixed-refrigerant system will not fix the short-cycling, will likely recur within weeks, and leaves the customer paying repeatedly for refrigerant. A compliant repair costs more up front but restores reliable capacity and avoids the safety and performance problems of an unknown blend. The technician should set out two priced options: repair the leak and retrofit to a compatible refrigerant with a full recover, evacuate and recharge; or replace the unit with a modern system. Either way the existing charge must be recovered, not vented. Records should capture the date, the system location, the refrigerant recovered and its weight, the cylinder used, the leak test result and the final charge amount and refrigerant type. These records support the customer, the technician's licence obligations and any future service. The technician should not let a tight budget override the no-venting and leak-repair duties.