Heater System Buick Skylark VII

DESCRIPTION & OPERATION

Fresh air enters system through air inlet at right end of instrument panel. Blower motor forces air through system. Temperature door controls air volume directed through heater core. Temperature door is controlled by a cable. Mode doors control whether air exits system from floor vents, face vents or defrost vents. Mode doors are controlled by vacuum motors.

Note. Equipped with dual air bags.

TEMPERATURE CONTROL CABLE

1. If temperature control knob fails to move to fully COLD or fully HOT positions or too much spring-back occurs, cable end eyelet will need to be adjusted. Adjust temperature control knob by moving to fully COLD or fully HOT positions. At about 2/3 of full travel, additional effort may be required. As control knob is brought to full position, a "click" may be heard, indicating adjustment is complete.
2. Temperature control knob operation should be uniform in both directions. If not, remove cable end from actuator and rotate cable end eyelet until cable end is flush with threaded eyelet hole. (Scheme 1) Install cable end to actuator and complete adjustment.

Scheme 1

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Scheme 6

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Scheme 8

TESTING

Note. Equipped with dual air bags.

BLOWER MOTOR DOES NOT OPERATE IN ANY SPEED

1. Check fuse. Replace fuse if blown or open (repair short to ground if necessary). If fuse is okay, turn ignition switch to RUN position. Leave blower switch connector attached. Turn mode selector to VENT position. Connect test light between ground and White wire terminal of blower switch connector (backprobe terminal).
2. If test light comes on, go to next step. If test light does not come on, connect test light between ground and Brown wire terminal of mode selector switch connector (backprobe terminal). If test light does not come on, repair open Brown wire. If test light comes on, repair open White wire between mode selector switch and blower switch.
3. Turn ignition on. Turn mode selector to VENT position. Turn blower switch to LOW position. Connect test light between connector C1 terminal "A" (Yellow wire) and ground. If test light does not come on, replace blower switch. If test light comes on, go to next step.
4. Ensure ignition is still on. Turn blower switch to LOW position. Turn mode selector to VENT position. Disconnect blower motor relay. Connect test light between terminal No. 87A (Dark Blue wire) and ground. If test light does not come on, check for open circuit in Dark Blue wire. If circuit is okay, replace blower resistor assembly. If test light comes on, go to next step.
5. Turn ignition off. Disconnect blower motor relay. Connect fused jumper wire between terminals No. 87A (Dark Blue wire) and No. 30 (Purple wire). Turn ignition on. Move mode selector to VENT position. Move blower switch to LOW position. If blower motor operates, replace blower motor relay. If blower motor does not operate, go to next step.
6. Ensure jumper wire is still connected. Disconnect blower motor connector. Connect test light between connector C1 terminal "B" (Purple wire) and connector C2 terminal "A" (Black wire). If test light comes on, replace blower motor. If test light does not come on, go to next step.
7. Ensure jumper wire is still connected. Disconnect blower motor connector. Connect test light between connector C1 terminal "B" (Purple wire) and ground. If test light comes on, repair open circuit in Black wire. If test light does not come on, repair open circuit in Purple wire.

BLOWER MOTOR OPERATES IN ALL SPEEDS EXCEPT HIGH

1. Disconnect blower motor relay connector (on right front strut tower). Connect test light between ground and Red wire terminal of blower motor relay connector. If test light does not come on, repair open Red wire. If test light comes on, connect test light between Red and Black wire terminals of blower motor relay connector.
2. If test light does not come on, repair open Black wire. If test light comes on, turn ignition switch to RUN position. Turn mode selector to VENT position. Set blower switch to high position. Connect test light between ground and White wire terminal of blower motor relay connector.
3. If test light comes on, replace blower motor relay. If test light does not come on, check for open White wire. If White wire is okay, replace blower switch.

BLOWER MOTOR OPERATES ONLY IN HIGH

1. Turn ignition switch to RUN position. Turn mode selector to VENT position. Turn blower switch to low position. Connect test light between ground and Yellow wire terminal of blower resistor connector. If test light comes on, go to next step. If test light does not come on, check for open Orange wire. If Orange wire is okay, replace blower switch.
2. Turn blower switch to medium-low position. Connect test light between ground and Tan wire terminal of blower resistor connector. If test light comes on, go to next step. If test light does not come on, check for open Tan wire. If Tan wire is okay, replace blower switch.
3. Turn blower switch to medium-high position. Connect test light between ground and Light Blue wire terminal of blower resistor connector. If test light comes on, go to next step. If test light does not come on, check for open Light Blue wire. If Light Blue wire is okay, replace blower switch.
4. Leave blower switch in medium-high position. Connect test light between ground and Dark Blue wire terminal of blower resistor connector. If test light does not come on, replace blower resistor. If test light comes on, check for open Dark Blue wire (blower motor relay is on right front strut tower). If circuit is okay, replace blower motor relay.

REMOVAL & INSTALLATION

Note. Equipped with dual air bags.

Disconnect negative battery cable. Remove trim plate. Remove heater control panel screws. Disconnect electrical and vacuum connectors. Remove heater control panel. (Scheme 9) To install, reverse removal procedure.

Scheme 9

HEATER CORE

1. Disconnect negative battery cable. Drain cooling system. Raise and support vehicle. Remove drain tube. Disconnect heater hoses from heater core. Lower vehicle.
2. Remove left and right sound insulators from below instrument panel. Remove steering column opening filler. On Skylark, remove console (if equipped). On all models, remove floor outlet duct. Remove heater core cover and heater core. (Scheme 10) To install, reverse removal procedure. Fill cooling system.

Scheme 10

1. Disconnect negative battery cable. On 3.3L, remove power steering pump from bracket and set aside. On all models, disconnect blower motor electrical connectors. (Scheme 11) Partially cut blower case cover as indicated by dashed line on cover ( DO NOT cut deeper than about 1/8" (3.2 mm), or blower motor cooling tube may be damaged). (Scheme 12)and (Scheme 13).
2. Open blower motor cover, leaving lower portion uncut, and remove blower motor cooling tube. Remove blower motor. To install, reverse removal procedure using 3 retaining clips on blower motor case.

Scheme 11

Scheme 12

Scheme 13