HVAC System - Cavalier & Sunfire Chevrolet Cavalier III

DESCRIPTION

Fresh air enters system through air inlet at right end of instrument panel. On 2.4L engine equipped models, a flow control valve or "H" valve is used to assist in heater warm up. Temperature door and heater valve control air discharge temperature. Temperature door and heater valve are controlled by cable.

Mode doors control whether air exits system from floor vents, panel vents or defrost vents. Air distribution is controlled by heater control panel and vacuum operated doors.

CONTROL PANEL

Several mode settings are available on the control panel to allow selection of a desirable comfort level. The available settings are as follows

1. OFF No blower operation in this position. With vehicle moving forward, a slight amount of air will enter passenger compartment.
2. Vent Outside air is delivered through dash registers.
3. Bi-Level Air is directed through dash registers and floor outlets. A small amount of air is directed to defroster outlets.
4. Heater Outside air is heated and distributed about 80 percent to floor and 20 percent to windshield and side windows.
5. Blend & Defrost In blend position, air is distributed to floor, windshield and side windows. In defrost position, air is distributed to windshield.

NO HEAT FROM VENTS

Check for proper temperature cable operation and adjustment. Check operation of heater valve, located in-line with heater hose. Check engine thermostat operation.

BLOWER MOTOR IS INOPERATIVE

Check for blown fuses. Check for loose connection at blower motor. Check operation of blower motor resistor.

IMPROPER AIR FLOW FROM VENTS

Check operation of mode switch. Check for vacuum leaks at mode switch, vacuum tank and in engine compartment.

BLOWER MOTOR IS INOPERATIVE IN ANY SPEED

Note. Check for open BLO fuse (30-amp), located in the underhood fuse/relay center and HVAC fuse (10-amp), located in instrument panel fuse block, before proceeding with diagnosis.

1. Turn ignition switch to ON position. Set heater control panel mode switch to vent position. Using a test light connected to ground, backprobe heater control panel mode switch connector C-3 terminal "B" (Brown wire). See «WIRING DIAGRAMS»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) . If test light does not come on, repair open Brown wire between heater control panel and HVAC fuse (10-amp) in instrument panel fuse block. Recheck blower motor operation. If test light comes on, go to next step.
2. Using test light, backprobe heater control panel mode switch connector C-3 terminal "C" (Brown wire). If test light comes on, go to next step. If test light does not come on, replace heater control panel mode switch.
3. Turn ignition off. Remove blower motor relay. Turn ignition switch to ON position. With heater control panel mode switch in vent position, connect test light between blower motor relay connector terminal No. 85 (Brown wire) and ground. If test light comes on, go to next step. If test light does not come on, check for open in Brown wire and repair as necessary. If power circuit (Brown wire) is okay, replace heater control panel. See «HEATER CONTROL PANEL»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation.
4. Connect test light between blower motor relay connector terminals No. 85 (Brown wire) and No. 86 (Black wire). If test light comes on, go to next step. If test light does not come on, check for open in Black wire between blower motor relay and ground connector on left side of engine. Recheck blower motor operation.
5. Connect test light between blower motor relay connector terminals No. 30 (Orange wire) and No. 86 (Black wire). If test light comes on, go to next step. If test light does not come on, go to step 7 .
6. Connect fused jumper wire between blower motor relay harness connector terminals No. 30 (Orange wire) and No. 87 (Purple wire). If blower motor does not operate, go to step 8 . If blower motor operates, replace blower motor relay. Recheck blower motor operation.
7. Check for open in Orange wire between blower motor relay and BLO fuse (30-amp) in engine compartment fuse block. If Orange wire is okay, check for open in Purple wire between blower relay and blower motor. Recheck blower motor operation.
8. Reinstall blower motor relay. Disconnect blower motor connector. Connect test light between blower motor connector terminal "B" (Purple wire) and ground. If test light comes on, go to next step. If test light does not come on, repair open Purple wire between blower motor and blower motor relay. Recheck blower motor operation.
9. Connect test light between blower motor connector terminals "A" (Orange wire) and "B" (Purple wire). If test light comes on, replace blower motor. See «BLOWER MOTOR»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. If test light does not come on, go to next step.
10. Reconnect blower motor connector. Connect test light between terminal "C" (Orange wire) and ground. If test light comes on, replace blower motor resistor. If test light does not come on, check for open in Orange wire.

BLOWER MOTOR DOES NOT OPERATE IN LOW POSITION

1. Turn ignition switch to ON position. Set heater control panel mode switch to vent position. Disconnect blower motor resistor. Set blower speed to low position. Connect fused jumper between blower resistor connector terminal "C" (Orange wire) and "D" (Black/White wire). See «WIRING DIAGRAMS»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) . If blower motor operates, go to next step. If blower motor does not operate, go to step 3 .
2. Replace blower motor resistor. See «BLOWER MOTOR RESISTOR»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation.
3. Reconnect blower motor resistor. Disconnect heater control panel connector C-2. Connect fused jumper wire between heater control panel connector C-2 terminal "A" (Black/White wire) and ground. If blower motor operates, Replace heater control panel. See «HEATER CONTROL PANEL»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation. If blower does not operate, repair open in Black/White wire between heater control panel and blower motor resistor. Recheck blower motor operation.

BLOWER MOTOR DOES NOT OPERATE IN MEDIUM-LOW POSITION

1. Turn ignition switch to ON position. Set heater control panel mode switch to vent position. Disconnect blower motor resistor. Set blower speed to medium-low position. Connect fused jumper wire between blower resistor connector terminal "A" (Tan wire) and "C" (Orange wire). See «WIRING DIAGRAMS»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) . If blower motor operates, go to next step. If blower motor does not operate, go to step 3 .
2. Replace blower motor resistor. See «BLOWER MOTOR RESISTOR»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation.
3. Reconnect blower motor resistor. Disconnect heater control panel connector C-2. Connect a fused jumper wire between heater control panel connector C-2 terminal "C" (Tan wire) and ground. If blower motor operates, go to next step. If blower does not operate, repair open in Tan wire between heater control panel and blower motor resistor. Recheck blower motor operation.
4. Replace heater control panel. See «HEATER CONTROL PANEL»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation.

BLOWER MOTOR DOES NOT OPERATE IN MEDIUM-HIGH POSITION

1. Turn ignition switch to ON position. Set heater control panel mode switch to vent position. Disconnect blower motor resistor. Set blower speed to medium-high position. Connect fused jumper wire between blower resistor connector terminal "B" (Light Blue wire) and "C" (Orange wire). See «WIRING DIAGRAMS»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) . If blower motor operates, go to next step. If blower motor does not operate, go to step 3 .
2. Replace blower motor resistor. See «BLOWER MOTOR RESISTOR»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation.
3. Reconnect blower motor resistor. Disconnect heater control panel connector C-2. Connect fused jumper wire between heater control panel connector C-2 terminal "B" (Tan wire) and ground. If blower motor operates, go to next step. If blower does not operate, repair open Tan wire between blower switch and blower motor resistor. Recheck blower motor operation.
4. Replace heater control panel. See «HEATER CONTROL PANEL»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation.

BLOWER MOTOR INOPERATIVE IN HIGH SPEED

Note. If blower motor only works in high speed, check blower resistor operation before continuing diagnosis.

1. Turn ignition switch to ON position. Set heater control panel mode switch to vent position. Set blower speed to high position. Disconnect heater control panel connector C-2. Connect a fused jumper wire between heater control panel connector C-2 terminal "D" (Orange wire) and ground. See «WIRING DIAGRAMS»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) . If blower motor operates, go to next step. If blower motor does not operate, go to step 3 .
2. Replace heater control panel. See «HEATER CONTROL PANEL»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) under REMOVAL & INSTALLATION. Recheck blower motor operation.
3. Repair open Orange wire between heater control panel and splice. Recheck blower motor operation.

BLOWER SWITCH

Disconnect heater control head. Using DVOM, check continuity of blower switch. See BLOWER SWITCH CONTINUITY table.

BLOWER SWITCH CONTINUITY

REMOVAL & INSTALLATION

Disconnect negative battery cable. Remove right sound insulator. Disconnect blower motor electrical connectors. (Scheme 11) Remove blower motor screws and lower blower motor out of housing. To install, reverse removal procedure. Torque all fasteners to specifications. See TORQUE SPECIFICATIONS.

Scheme 11

Disconnect negative battery cable. Remove right sound insulator. Remove blower motor. See BLOWER MOTOR. Disconnect blower resistor. (Scheme 11) Remove resistor screws and blower resistor. To install, reverse removal procedure.

Disconnect negative battery cable. Remove accessory trim plate. Remove screws and pull heater control panel out. (Scheme 12) Disconnect electrical connectors, vacuum lines and control cable from heater control panel. Remove heater control panel. To install, reverse removal procedure.

Scheme 12

HEATER CORE

1. Disconnect negative battery cable. Drain cooling system. Raise and support vehicle. Remove heater hoses from heater core. Lower vehicle.
2. Remove instrument panel. See «INSTRUMENT PANEL»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire). Remove heater module. (Scheme 13) Turn module over and remove heater core cover and heater core. (Scheme 14)
3. To install, reverse removal procedure. Torque all fasteners to specifications. See «TORQUE SPECIFICATIONS»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire__torque-specifications). Fill cooling system and check for leaks.

Scheme 13

Scheme 14

1. Disconnect negative battery cable. Unclip defrost grille. Remove instrument panel end caps. Remove screws from under end caps. Open glove box and remove screws for glove box and accessory trim plate.
2. Remove screws from bracket support at upper left corner of glove box. Remove accessory trim plate. Remove hex head screws attaching instrument panel trim pad to instrument panel. Remove instrument panel trim pad.
3. Remove instrument cluster trim plate screws and trim plate. Remove instrument cluster screws, disconnect electrical connector and remove instrument cluster. Remove heater control panel. See «HEATER CONTROL PANEL»(/chevrolet/cavalier/iii-1995-2005/remont/heater/#hvac-system-cavalier-sunfire) . Remove radio assembly.
4. Remove air distribution ducts. Remove steering wheel from steering column. Disconnect instrument panel compartment light electrical connector.
5. Remove tie bar screws. Remove instrument panel from tie bar. Remove 2 bolts and remove tie bar from vehicle. To install, reverse removal procedure.

Remove right sound insulator. Disconnect cable from heater module. Remove heater control panel. See HEATER CONTROL PANEL. Disconnect heater cable from heater control panel. (Scheme 14) To install, reverse removal procedure. Torque all fasteners to specifications. See TORQUE SPECIFICATIONS.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Heater System Wiring Diagram (2000 Cavalier & Sunfire). Scheme 15

See also:
• WIRING DIAGRAMS
• TORQUE SPECIFICATIONS