DESCRIPTION
System is a blend air type. Outside air is heated and then mixed with cooler outside air to attain desired temperature. System consists of blower and air inlet assembly, heater air distributor assembly and heater control panel.
Blower and air inlet assembly and heater hoses are located on the engine side of dash panel while heater core and distributor duct are on passenger side. System has no heater control valve. Coolant circulation keeps heater core hot at all times.
Operation of blower motor is controlled by the fan switch. The motor is connected in series with the fan switch and blower resistor assembly.
Temperature Control Lever
The lower lever on the control panel controls discharge air temperature in all Mode Control Lever positions. Full right position provides maximum heat. Full left position provides cool (outside) air.
Mode Control Lever (Standard System)
When in "OFF" position, the system is off. When in "HEATER" position, most of the air is delivered through the floor (heater) outlet with some air flow to the windshield (defroster) outlets.
The lever may be adjusted between "HEATER" and "DEF" to vary air distribution between floor air outlet and windshield outlet. In the "DEF" position, heated air is delivered to the windshield outlets with a small amount to the floor outlets.
Mode Control Lever (Optional System "S" Models)
When this lever is in the "VENT" position, all discharge air is directed to the upper outlets. The "DEF" position directs most of the air to the windshield (defroster) outlets with some directed to the floor (heater) outlets. When in "HEATER" position, most of the air is delivered through the floor outlets with some air flow to the windshield outlets.
Blower Control
Blower control can be either knob or lever. Knob is a 4-speed type rotating from "OFF" to "HI". Lever is a variable speed type, sliding from "OFF" through "LO" to "HI".
Auxiliary Heater Blower Switch
A 3-speed blower switch is located in the instrument panel to the right of steering column. When switch is in "OFF" position, auxiliary system will not operate.
Heater Control Panels. Scheme 1
Astro Van Auxiliary Heater. Scheme 2
"S" Models
Remove control panel. Disconnect control cables at both ends. Replace cables and install control panel. Cycle control lever through its full range of travel to adjust cable. (Scheme 3)and (Scheme 4).
TROUBLE SHOOTING & DIAGNOSIS
See the GENERAL MOTORS HEATERS - TROUBLE SHOOTING & DIAGNOSIS article in this section.
Removal & Installation ("S" Models)
Disconnect battery ground. Remove instrument panel center bezel. Remove control panel screws and pull control out. Disconnect electrical connection and cables from control panel. Remove blower switch from control panel. To install, reverse removal procedure.
HEATER CORE
Note. These procedures are for vehicles with heater systems only. For vehicles with manual A/C-heater systems, see MANUAL A/C SYSTEMS article.
Disconnect battery ground cable. Drain engine coolant. Remove heater core hoses at core and plug core openings. Remove core cover attaching screws. Remove retainers at ends of core (4 screws). Remove core from vehicle. To install, reverse removal procedure.
Disconnect negative battery cable. Disconnect electrical connectors at blower motor. Remove blower motor retaining screws and remove blower motor. To install, reverse removal procedure.
Disconnect negative battery cable. Pull control panel out from dash. Disconnect cables at control panel and heater module. Remove cables. To install, reverse removal procedure. (Scheme 3)and (Scheme 6).
