That vehicle can have two different systems installed, one with the knobs and one with electronic control. In both cases, the blend door (Hot/Cold) is controlled by an electronic blend door actuator. Air distribution doors (Defrost/Floor/Face) are controlled by engine vacuum. Here are the Procedures for removal of the blend door.
1. Disconnect battery ground cable.
2. Disengage console panel from instrument panel reinforcement and remove from instrument panel.
3. Disengage console panel from RH side of center console finish panel if equipped.
4. Working from under the passenger side of the instrument panel, remove A/C electronic blend door actuator electrical connector from A/C electronic blend door actuator.
5. Remove four screws retaining A/C electronic blend door actuator to the A/C evaporator housing and remove A/C electronic blend door actuator from A/C air temperature control door.
Here are the Procedures for removal of the heater core.
1. Remove instrument panel NOTE: If a heater core leak is suspected, the heater core must be leak tested before it is removed from the vehicle.
2. Drain coolant from radiator into a clean container.
3. Disconnect heater water hoses from heater core. Plug heater core tubes or blow any coolant from heater core with low pressure air.
4. Remove four retaining screws and A/C electronic blend door actuator from A/C evaporator housing.
5. Remove metal cover, disengage spring from heater core cover and remove spring from lever.
6. Gently depress locking ramp and remove lever from secondary A/C air temperature control door end. NOTE: Do not attempt to bend any part of the lever. It is brittle and will break.
7. Rotate primary A/C air temperature control door shaft down, then swing metal link and remove from pin.
8. Remove three heater core cover retaining screws and remove heater core cover and heater core cover seal from A/C evaporator housing.
9. Remove heater core and seal from A/C evaporator housing by pushing on heater core tubes.
A scan tool will tell you if the blend door has set a Diagnostic Trouble Code if you have the electronic system. If you have the manual system, visual confirmation of the bend door actuator movement is the only way to verify operation.
Yes, a lot of guys just loosen things enough to get it out of the way so the best thing to do is just look at it as you go and decide if something really needs to come off or not.
Make sure the coolant is topped off, and the heater core hoses are HOT. 120 degrees at least, after the thermostat has opened (top rad hose hot). Don’t use draino! If it wasn’t leaking before, it may after. Just use the garden hose in the outlet side and run it until you see clear water running out of the inlet. After that, hook the hoses back up. That is a self bleeding system so you can just top off the coolant and run the engine until the thermostat opens with the heater in full heat position. Keep adding coolant as it warms up as trapped air is purged. Man, that was long.