Honda Odyssey Service Manual: A/C Compressor Relief Valve Replacement

Recover the refrigerant with a recovery/recycling/charging station.

Remove the relief valve (A) and the O-ring (B). Plug the opening to keep moisture and foreign material from entering the system and the A/C   compressor oil from running out.

Clean the mating surfaces.

Replace the O-ring with a new one at the relief valve, and apply a thin coat of refrigerant oil before installing it.

Remove the plug, and install and tighten the relief valve.

Charge the system.