Q: How to Replace the Air Conditioning Pressure Switch and O-Ring Seal on Infiniti G35?A: Have the air conditioning system discharged by a dealer service department or an automotive air conditioning shop before proceeding (Warning above). Remove the radiator grille (from the bumper cover) and unplug the electrical connector from the air conditioning pressure switch (Unplug the electrical connector, then unscrew the switch). On 2007 and later G35 Sedan models, unscrew the pressure switch from the top of the receiver-drier and discard the 0-ring seal. On all other models, unscrew the pressure switch from the condenser above the receiver-drier and discard the 0-ring seal. Lubricate a new R-134a compatible 0-ring seal with the appropriate refrigerant oil and place it into position, install the new switch until hand tight, and then tighten it securely. Have the system evacuated, recharged and leak-tested by the shop that discharged it.