Heater System Chevrolet Astro I

DESCRIPTION

System blends heated outside air with cooler outside air to obtain desired temperature. Major components of the system are a blower motor, air inlet assembly, heater air distributor assembly, and heater control panel.

AUXILIARY HEATER BLOWER SWITCH

A 3-speed blower switch (if equipped) is located on instrument panel, to right of steering column. When switch is in OFF position, auxiliary system does not operate.

BLOWER SPEED SWITCH

The blower speed knob selects low, medium, or high blower speed.

MODE SELECTOR

The mode selector directs discharge air to windshield, floor, or dash outputs, as desired by driver.

TEMPERATURE CONTROL SELECTOR

The temperature control lever or knob controls discharge air temperature in all mode positions. Full hot position provides maximum heat. Full cold position provides unheated air.

VENT Mode

Air is directed to instrument panel outlets.

BI-LEV Mode

Air is directed to instrument panel and floor outlets. A slight amount of air is directed to defroster and side window defogger outlets.

HEAT Mode

Air is diverted to floor outlets to heat passenger compartment. A slight amount of air is directed to windshield and side window defogger outlets. BLEND Mode

Air is divided between instrument panel and floor outlets, with a slight amount of air going to defroster outlets.

DEF Mode

Air is directed to windshield defroster outlets. A slight amount of air is diverted to floor outlets and side window defogger outlets.

ADJUSTMENTS

Note. Information on temperature control cable adjustment is not available from manufacturer.

TROUBLE SHOOTING

Note. For Trouble Shooting information not covered in this article, refer to the A/C-HEATER SYSTEM article in the AIR CONDITIONING & HEAT section.

Note. Before performing trouble shooting procedures, ensure HTR/AC fuse is okay.

BLOWER MOTOR INOPERATIVE

1. Disconnect blower motor connector. Turn ignition on. Set blower switch to high speed position. Connect test light between Orange wire at blower motor connector and ground. If test light glows, go to next step. If test light does not glow, go to step 3).
2. Connect test light between Orange wire and Black wire at blower motor connector. If test light glows, replace blower motor. If test light does not glow, repair open Black wire between blower motor connector and ground.
3. Connect test light between Brown wire at blower switch connector and ground. If test light glows, go to next step. If test light does not glow, repair open Brown wire between blower switch connector and fuse block.
4. Set blower switch to low speed, medium speed, or high speed position. Connect test light between ground and blower switch connector wire associated with switch position. Low speed position is Yellow wire, medium speed position is Light Blue wire, and high speed position is Orange wire. If test light does not glow, replace blower switch. If test light glows, repair open wire(s) between blower switch and blower resistor.

BLOWER MOTOR OPERATES AT LOW &/OR MEDIUM SPEED ONLY

1. Turn ignition on. Set blower switch to high speed position. Connect test light between Orange wire at blower switch connector and ground. If test light glows, go to next step. If test light does not glow, replace blower switch.
2. Connect test light between Orange wire at blower resistor connector and ground. If test light glows, replace blower resistor. If test light does not glow, repair open Orange wire between blower resistor and blower switch.

BLOWER MOTOR OPERATES AT HIGH SPEED ONLY

1. Turn ignition on. Set blower switch to speed that does not operate. Connect test light between wire of inoperative speed position at blower switch connector and ground. Low speed is Yellow wire; medium speed is Light Blue wire.
2. If test light does not glow, replace blower switch. If test light glows, connect test light between Yellow wire or Light Blue wire (depending on switch position) at blower resistor connector and ground.
3. If test light does not glow, repair open Yellow wire or Light Blue wire between blower resistor and blower switch. Go to next step if test light glows.
4. Connect test light between Orange wire at blower resistor and ground. If test light glows, circuit is okay. If test light does not glow, replace blower resistor.

Scheme 1

Scheme 2

AUXILIARY BLOWER MOTOR INOPERATIVE

Note. For rear auxiliary heater system test information, refer to the A/C-HEATER SYSTEM article in the AIR CONDITIONING & HEAT section.

REMOVAL & INSTALLATION

Disconnect negative battery cable. Unplug blower connector. Remove coolant recovery tank. Remove bolts from windshield washer reservoir, and secure reservoir aside. Remove blower motor. To install, reverse removal procedure.

1. Disconnect negative battery cable. Remove screws from bottom of control panel. Pull control assembly away from instrument panel.
2. Disconnect control cables. Unplug blower switch connector. Remove control assembly. Remove blower switch knob and retaining clip. Remove blower switch. To install, reverse removal procedure.

HEATER CORE

Disconnect negative battery cable. Drain engine coolant. Remove heater hoses at core. Remove lower distributor duct. Remove defroster outlet duct. Remove heater case cover screws. Remove heater core. (Scheme 3) To install, reverse removal procedure. Fill cooling system. Start engine and check for leaks.

Scheme 3

Disconnect negative battery cable. Pull control assembly from dash. (Scheme 4) Disconnect cables at control assembly and heater assembly. Remove cables. To install, reverse removal procedure.

Scheme 4

AUXILIARY BLOWER MOTOR

Disconnect negative battery cable. Heater assembly is located on left side of vehicle, forward of left rear tire. Remove cover screws and cover. Unplug connector from blower motor. Remove blower motor. To install, reverse removal procedure.

Disconnect negative battery cable. Remove instrument panel trim panel. Unplug connector. Remove control switch. To install, reverse removal procedure.

Disconnect negative battery cable. Drain engine coolant. Heater is located on left side of vehicle, forward of left rear tire. Disconnect heater hoses from heater core. Remove heater cover. Remove mounting straps. Remove heater core. To install, reverse removal procedure. Fill cooling system. Start engine and check for leaks.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• A/C-HEATER SYSTEM