Ford 2003 Mustang Workshop Manual page 3097

3. CAUTION: Use only the new O-ring seals. The use of any O-ring seals other than
those specified in the Ford Master Parts Catalog may result in intermittent leakage
during vehicle operation.
Install the O-ring seals.
Lubricate the O-ring seals with PAG Refrigerant Compressor Oil (R-134a Systems) or
equivalent.
4. Connect the spring lock coupling fittings with a twisting motion until the A/C tube lock coupling
spring snaps over the flared end of the female fitting.
5. Install the A/C tube lock coupling clip.