R-134a service equipment or vehicle A/C system should not be pressure tested or leak tested with compressed air. Mixture of air and R-134a can be combustible at elevated pressures. These mixtures are potentially dangerous and may result in fire or explosion causing property damage and possible serious or fatal injury.
Avoid breathing A/C refrigerant and lubricant vapor or mist. Exposure may irritate eyes, nose and throat. Use only approved service equipment meeting SAE requirements to discharge an R-134a system. If accidental system discharge occurs, ventilate work area before resuming service.
If the A/C system refrigerant charge is empty or low, a leak in the A/C system is likely. Visually inspect all A/C lines, fittings and components for an oily residue. Oil residue can be an indicator of an A/C system leak location.
The only way to correctly determine if the A/C system is fully charged with refrigerant to perform the A/C Performance Test.
Connect a suitable manifold gauge set and determine if the static A/C system pressure is above or below 50 psi (345 kPa). If less than 50 psi (345 kPa), proceed to System Empty. If greater than 50 psi (345 kPa), go to System Low.