You see it them at auto shops and truck stops: one-pound cans of R-134a, the kind with a hose you can hook up to charge the air conditioner. Typically, there are three varieties: R-134a with oil for the compressor; R-134a with oil and sealant; and straight R-134a.
Each type can do more harm than good.
For example, the oil mixed with R-134a may not match the compressor’s original PAG or ester oil specification. If the compressor lunges, the manufacturer will analyze the oil for its type and viscosity. If it detects an oil that’s different from the original, it will void the warranty.
R-134a with sealant is worse. As it circulates through the system, the sealant will solidify when it encounters a leak. Sealant also can collect inside valves and tubes, clogging them up. Furthermore, it can harm refrigerant recovery and recycling equipment. Many A/C technicians will refuse to work on a vehicle if their refrigerant identifiers detect 134a with sealant.
So why not use a one-pound can of straight R-134a? First, you don’t know if you need one pound of refrigerant or some other amount to replenish your A/C system. Second, if your system is losing refrigerant charge, you need to find out why.
There’s no such thing as A/C service in can. What seems like a quick fix really is an invitation to an expensive, time-consuming repair. See a qualified technician if you think your system is losing its charge.