In servicing A/C and heater systems you will be exposed to high pressures, temperatures and several chemical hazards. Moving belts and pulleys are normal shop hazards.
In addition to exercising caution in your work, DO WEAR SAFETY GLASSES OR A FACE SHIELD [Figure 70-10-12] when you are using R-134a or a leak detector, adjusting service valves or the manifold gage set connectors. Safety glasses or a transparent face shield are practical safety items and one or the other is absolutely required.
R-134a inside a canister or in an A/C system is a liquid under pressure. When it escapes or releases into the air, ITS TEMPERATURE DROPS TO -5.7°C (21.6°F) “INSTANTLY”.
If it spills on your skin or in your eyes you should flood the area with cool water and SEEK MEDICAL ATTENTION FAST! It is a good idea to wear gloves [Figure 70-10-13] to prevent frost bite if you should get refrigerant on your hands.