The expansion valve is located in the evaporator housing of the cooling unit, and in some applications, the evaporator assembly must be replaced along with the expansion valve. Begin by properly discharging the air conditioning system using freon recovery equipment. Next, remove the evaporator core and cooling unit assembly following the necessary service procedures, then take out the expansion valve from the evaporator core. For installation, reverse the removal steps, ensuring that the seals between the housings are in good condition and replacing them as necessary. Always use new O-rings on the freon line fittings. Finally, evacuate and charge the system as required, ensuring the oil level is correct for the system, and consult the necessary illustration charts of NC General Specifications.