Uv dye
You track down an aircon losing refrigerant with UV leak detection fluid. This additive mixes with the PAG oil and circulates with the refrigerant. Where it escapes the system, it leaves a trace you can see with a UV lamp. The fluid suits R-134a and R-1234yf and is dosed by 7.5 ml syringe. For a system that has been losing charge for a while, a leak stop is a different route from tracing.
UV leak detection fluid: dosing, choosing and ordering
Which dose suits your system
The dose depends on how much refrigerant is in the system. The syringes hold 7.5 ml each, so you take as many as the fill quantity calls for. The fluid suits R-134a and R-1234yf. For larger systems there are 250 ml and 1000 ml bottles, so you do not have to work with loose syringes.
PAG or POE: which carrier do you need
The carrier of this additive is PAG oil. That suits systems running on PAG oil. If you drive a hybrid or electric with an electric compressor, that calls for POE oil. So check first which oil is in the system before you top anything up.
From syringe to set: what you get
Loose 7.5 ml syringes are there for a single service. The fluid is not hazardous under EC 1272/2008 (CLP). After tracing, dye remains in the system. To flush out a system where the colour has to go, you use a UV remover. When ordering, look at the refrigerant in the system and at the quantity you need.