Heater problems

Item 16 should have vacuum going to it whenever a/c is on that shuts off water flow its' under hood.

Did you put in a 195 degree tstat? And yes a clogged core can do this in early stages. Have a radiator shop blow the core out. When the heat gets cold is one heater hose(outlet) cold? If so, the core is plugged, if both are cold, the tsat, or low coolant level is your problem.

Actuator can be removed without removal of instrument panel. Remove console and the lower
steering column cover. Then remove in sequence shown in picture. Upper bolt can be
accessed through a hole just below, and to the right of column

Hi there,

If your engine temp is still running normal on the gauge the thermostat should be ok. Check the heater hoses, are they both hot to touch, if not the heater tap or the control for the tap may of failed check this first.

Mark (mhpautos)

Chances are your blend door is sticking due to insufficent vaccum due to a bad vaccum hose or a bad electrical motor that controls the blend door ( it is a dealer only part).

Could even be the switch.

Check to ensure your coolant level is up to normal. Also, if the head gasket is weak, it may allow engine coolant to seap into a cylinder and be thrown out through the exhaust. The engine may operate normally but there would more than likely be little or no heat, except there would be a tail-tail sign of a LOT of smoke coming from your exhaust. Check to see if both hoses connected to the radiator are getting hot. If only one is getting hot then you may have a clogged heater core.

OPERATION
CONTROL PANEL & DOOR ACTUATORS
Manual A/C-heater control panel is located near center of the instrument panel. A/C-heater controls include a function selector knob, temperature control knob and blower speed control knob. See Fig. 1. Function selector knob actuates a vacuum selector valve that controls vacuum to door actuators. Door actuators control position of outside/recirculation, floor/panel and panel/defrost doors. Door positions determine airflow modes (panel, floor, defrost, etc.).
Temperature control knob controls an electric blend door actuator. Blend door actuator controls the position of blend door. Blend door position determines airflow around and/or through heater core. Each function selector knob setting affects system operation is as follows:
OFF
Vacuum is applied to inlet duct door, preventing outside air from entering system. Heater water control valve is at full vacuum, preventing hot coolant from reaching heater core. Vacuum is applied to floor/panel and panel/defrost door actuators. Blower motor and compressor will not operate in this mode.
MAX A/C
A/C compressor operates in this mode. Vacuum is applied to air inlet door, preventing outside air from entering system. Heater water control valve is at full vacuum, preventing hot coolant from reaching heater core. Vacuum is applied to floor/panel and panel/defrost door actuators. Airflow exits from panel vents. Blower motor is on.
A/C
A/C compressor operates in this mode. Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Vacuum is applied to floor/panel and panel/defrost door actuators. Airflow exits from panel vents. Temperature setting can be changed manually. Blower motor is on.
Vent
Vacuum is not applied to air inlet door, allowing outside air into system. Vacuum is not applied to floor/panel door actuator. Vacuum is applied to panel/defrost door actuator. Airflow exits from panel vents. Temperature can be adjusted manually.
Floor/Panel
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Partial vacuum is applied to floor/panel door actuator allowing door to open partially. Vacuum is applied to panel/defrost door actuator. Airflow exits from panel vents. The A/C compressor operates in this mode.
Floor
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Vacuum is applied to floor/panel door actuator. Vacuum is not applied to panel/defrost door actuator. Airflow exits from floor ducts.
Floor/Defrost
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Partial vacuum is applied to floor/panel door actuator. Vacuum is not applied to panel/defrost door actuator. A/C compressor operates to dehumidify air and reduce windshield fogging. Airflow exits from panel vents and floor ducts.
Defrost
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. No vacuum is applied to floor/panel door actuator or to panel/defrost door actuator. A/C compressor operates to dehumidify air and reduce windshield fogging. Airflow exits from defrost outlets.

Sorry i don't have a diagram of damper operation

fig 1

let me know if you need anything else !