The disassembly of the heater control housing is the same for Civics and CR-Vs and is described for typical heater core removal, the air conditioning system, if applicable, should be depleted if possible, ideally by a dealer or automotive shop. Then, remove the cable away from the negative terminal and empty the cooling system of their content. Disconnect evaporator side AC line mounting bolts in engine compartment and disconnect AC evaporator lines at the dash from TXV, also remove the heater hoses from the heater core. Unscrew the heater control unit mounting nut and you will find that it is located inside the engine compartment and be careful not to harm any of the adjoining fuel or brake line facilities. The instrument panel is then taken off and the
Blower Motor and power transistor electrical connectors is disconnected. The mounting bolts to the heater/air conditioning assembly need to be pulled out, the electrical connectors have to be disconnected and the assembly has to be pulled out of the vehicle. Slide the carpet back to access and disconnect the evaporator drain hose from the firewall, also, set the blower apart from the heater/AC housing. It is followed by the removal of the passenger's heater duct screws together with the duct and finally the heater core cover screws. If there is air conditioning then remove the expansion valve cover fasteners and seal is required. Take off the screw and the bracket joining the heater pipe and after that remove the top heater cover that is on the heater /AC assembly. The process of installation is the same way as removal with a special care given to the heater core inlet and outlet hoses which must be connected to the firewall. Last but not least, connect the battery and add coolant to the vehicle's cooling system and if the air conditioning system was discharged, take it to the shop that conducted the discharge and get it evacuated, leak tested and recharged.