GM 22784517 Core Assembly, Heater

To remove the heater core in a 1999 Deville, start by disconnecting the cable from the negative terminal of the battery and draining the cooling system. The heater core is located in the passenger compartment, under the instrument panel. Disconnect the heater hoses at the firewall and remove the instrument panel to access the heater core cover. Disconnect the rod from the programmer to the blend-air door and disconnect the vacuum and electrical connectors from the programmer. Remove the heater core cover mounting screws and pull the cover away from the heater housing. Remove the two core mounting screws and carefully lower the heater/air conditioning assembly from under the dash. Installation is the reverse of removal. For a 1999 Seville or 2000-2005 model, the heater core is also located in the passenger compartment, behind the instrument panel. Disconnect the heater hoses at the firewall and remove the instrument panel. Remove the heater core cover mounting screws and pull the cover away from the HVAC assembly. Remove the heater core retaining straps and mounting screws, then remove the heater core from the HVAC assembly. Installation is the reverse of removal. For 2006 and later models, the heater core is contained in the HVAC assembly, which includes the heater core, evaporator core, and various mode doors and actuators. Have the air conditioning discharged by a qualified technician. Remove the right engine mount strut, windshield washer fluid heater, engine trim cover, and upper tie bar in the engine compartment. Disconnect the evaporator hose and heater hoses from the core. Remove the brake pedal assembly and reposition the carpet to allow room to move the HVAC assembly. Remove the instrument panel center support bracket and reposition the auxiliary air duct. Remove the instrument panel carrier and disconnect the HVAC assembly electrical connectors. Remove the heater core-to-NC pipe cover screws and remove the heater core. Installation is the reverse of removal.

The negative battery cable should be disconnected and the coolant drained and recycled to remove and install the heater core in Cadillac DeVille and Fleetwood models. Use tool J-37097 or equivalent to disconnect the heater core hoses. Remove the right side sound insulator, glove box module (also programmer shield if equipped), air mix valve link. Unplug the programmer vacuum, electrical connections as well as any connector on the harness wiring leading to the front side of the unit. Leave programmer with heater core cover removed. Proceed to remove the retaining screws on the heater core and then finally take it out from its place. To install, fix new heater core using retaining screws before joining with heater core cover. Make sure that you reconnect your air mix valve by attaching the programmer vacuum and electrical connectors and then also your air mix valve link. If there is a programmer shield, install it as well. Do not forget that you will need to connect your heater core hoses back on, therefore don't miss that one too, besides do not forget to connect up your negative battery cable and fill in cooling system thereafter. Make necessary adjustments as stated for your air mix valve, reinstalling right side lower sound insulator together with glove box module will finish everything off. This method should be followed in Eldorado and Seville models too. Negative battery cable must be disconnected first; besides engine coolant has to be drained off again so that it is re-cycled later. Glove box unit together with right side lower sound insulator should be removed completely while dealing with El Dorado/Seville models of Cadillac cars as well as Oldsmobile Aurora 1995-99 model years cars that have black cast nylon filler strips installed above or below glove box units hanging down from passenger's side dash panel below windshield area. Take out all of those items shown in this image: programmer , threaded rod , vacuum connector retaining nut, and vacuum and wiring connectors . The programmer should then be removed, while for early vehicles it is necessary to take the wiring connectors off the BCM/PCM . At this point remove mounting brackets if they are still there in case of older models or proceed to step 4 in case of all other vehicles. Take off heater core cover after disconnecting heater hoses and removing retaining screws . Fit in a new unit referred to as programmer, which may require connection of all remaining components together with refilling the cooling system. Finally, adjust your air mix valve as directed and then reinstall both right side lower sound insulator and even glove box unit thus completing an entire installation process.

Check for a loose cooling system hose clamp or leaking coolant hose near the engine firewall or under the dash, and repair as necessary. Look for a sweet odor and fluid dripping from the heater floor vents, which may indicate a failed or damaged heater core.

The right side sound insulator, glove box module, and programmer shield (if equipped) need to be removed. The air mix valve link, programmer vacuum and electrical connectors also need to be detached.

Check the blower motor fuse and replace it if necessary. Inspect the wiring for loose, damaged, or corroded contacts and repair as needed. Examine the blower motor switch and resistor pack for open circuits, and repair or replace them if required.