Heater System Chevrolet Beretta I

MODEL IDENTIFICATION

Adjustment and repair procedures in this article are referred to by either model or body type. Following table lists General Motors model name and body designations.

BODY/MODEL DESIGNATIONS

GENERAL MOTORS BODY/MODEL DESIGNATIONS

Scheme 1

SYSTEM DESCRIPTION

System is a blend-air type in which 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) assembly.

Heating components are attached to firewall on right side of vehicle. Blower motor, air inlet assembly and coolant hoses are located on engine side of firewall. Heater core and distributor duct are on passenger side. Since system has no heater control valve, coolant circulation keeps heater core hot at all times. Air passing through core receives maximum heat.

Operation of blower motor is controlled by fan switch. Motor is connected in series with fan switch and blower resistor assembly. A 25-amp fuse is provided to protect blower circuit operation. Heater control panel includes 2 sliding levers and a blower speed switch. Levers actuate cables that control heater mode and discharge air temperature.

VENT-HEATER-DEFROSTER LEVER OPERATION

This controls position of defroster door and vent-air door. In VENT position, blower is on (on some models) and incoming air is directed up through instrument panel. As lever is moved toward HEATER position, vent-air door closes, directing air into distributor assembly.

In HEATER position, defroster door directs most air to floor outlets with a small amount directed to dash registers. In DEF (defrost) position, air is directed to defroster outlets with a small amount directed to floor outlets. Moving lever part way will split air between defroster outlets and heater outlets.

TEMPERATURE LEVER OPERATION

Controls position of temperature door in heater distributor. Incoming air is directed around heater core in COLD position or through heater core in HOT position. Desired outlet temperature is obtained by blending heated and unheated air through adjustment of temperature lever.

FAN SWITCH OPERATION

Several types of fan switches are used. On models with a switch that has LO, MED and HI positions, fan operates at any time ignition is on. Some models have a variable position switch that has OFF and HI positions and intermediate positions marked with dots. Other models have a variable fan switch, with fan speed increasing as lever is pushed up from OFF toward HI position.

VENTILATION SYSTEM OPERATION

Continuous ventilation is provided when mode lever is in VENT position. Vehicle movement may create airflow through inside of car even when fan is off.

AIR BAG DEACTIVATION

DISABLING SYSTEM

Turn ignition OFF and remove air bag fuse No. 3. in Electrical Convenience Center. Remove left sound insulator. Remove Connector Position Assurance (CPA) and disconnect Yellow 2-way air bag harness connector at base of steering column. (Scheme 2)

Scheme 2

AIR BAG SYSTEM FUNCTIONAL CHECK

Reconnect Yellow 2-way harness connector at base of steering column and install CPA. Install sound insulator and air bag fuse No. 3. Turn ignition switch to RUN and ensure INFLATABLE RESTRAINT light flashes 7-9 times and then goes out. If INFLATABLE RESTRAINT light operates other than described, air bag system is malfunctioning and needs repair.

TROUBLE SHOOTING

Note. See appropriate TROUBLE SHOOTING article.

TESTING

BLOWER MOTOR TEST ("A", "F", "J" & "N" BODY)

1. Disconnect blower motor. Place ignition switch in RUN position, blower switch on HI, and heater in VENT mode. Measure voltage between Orange wire and ground. If battery voltage is present, go to BLOWER SWITCH TEST. If battery voltage is not present, check Orange wire for an open circuit.
2. Measure voltage between Orange wire and Black ground wire. If battery voltage is present, but blower motor does not run, replace blower motor. If battery voltage is not present, check Black ground wire for an open circuit. Ensure ground connections are clean and tight.

BLOWER MOTOR TEST ("L" & "W" BODY)

1. Disconnect blower motor. Place ignition switch in RUN position, blower switch on HI, and heater in VENT mode. Measure voltage between Purple wire and ground. If battery voltage is present, go to HIGH SPEED BLOWER RELAY TEST. If battery voltage is not present, check Purple wire for an open circuit.
2. Measure voltage between Purple wire and Black ground wire. If battery voltage is present, but blower motor does not run, replace blower motor. If battery voltage is not present, check Black ground wire for an open circuit. Ensure ground connections are clean and tight.

HEATER BLOWER RELAY TEST ("L" BODY)

1. With heater blower relay disconnected, ignition ON and blower switch at "3", measure voltage between Brown wire and ground. If battery voltage is present, replace heater blower relay. If battery voltage is not present, check Brown wire for an open circuit.
2. With heater blower relay disconnected, ignition ON and blower switch at "4", measure voltage between Orange wire and ground. If battery voltage is present, replace heater blower relay. If battery voltage is not present, check Orange wire for an open circuit.
3. With heater blower relay disconnected, ignition ON and blower switch at "4", measure voltage between Red wire and ground. If battery voltage is present, replace heater blower relay. If battery voltage is not present, check Red wire for an open circuit.
4. With heater blower relay disconnected, ignition ON and blower switch at "4", measure voltage between Red and Black wires. If battery voltage is present, replace heater blower relay. If battery voltage is not present, check Black wire for an open circuit.
5. With heater blower relay disconnected, ignition ON and blower switch at "4", measure voltage between Red and Purple wires. If battery voltage is present, replace heater blower relay. If battery voltage is not present, go to BLOWER MOTOR TEST.

HIGH SPEED BLOWER RELAY TEST ("W" BODY)

1. Disconnect high speed blower relay (on convenience center). Place ignition switch in RUN position, blower switch on HI, and heater in VENT mode. Measure voltage between Red wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Red wire for an open circuit.
2. Measure voltage between Orange wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Orange wire for an open circuit.
3. Measure voltage between Dark Blue wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Dark Blue wire for an open circuit.
4. Measure voltage between Orange wire and Black ground wire. If battery voltage is present, replace blower relay. If battery voltage is not present, check Black ground wire for an open circuit. Ensure ground connections are clean and tight.

LOW SPEED BLOWER RELAY TEST ("W" BODY)

1. Disconnect low speed blower relay (on convenience center). Place ignition switch in RUN position and heater in OFF mode. Measure voltage between Brown wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Brown wire for an open circuit. If wire is okay, check A/C fuse No. 2.
2. Measure voltage between Yellow wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Yellow wire for an open circuit. If wire is okay, go to HEATER CONTROL ASSEMBLY BLOWER CONTROL TEST.
3. Place heater in any position other than OFF. Measure voltage between Yellow wire and ground. If voltage is zero, go to next step. If voltage is other than zero, check Yellow wire for a short circuit to voltage source. If wire is okay, replace heater control assembly.
4. Place ignition switch in OFF position, blower switch on HI, and disconnect negative battery cable. Measure resistance between Black wire and ground. If reading is zero ohms, go to next step. If reading is not zero ohms, check Black wire for an open circuit.
5. Measure resistance between Yellow wire and ground. If reading is less than 10 ohms, replace low speed blower relay. If reading is more than 10 ohms, check Yellow wire for an open circuit. If wire is okay, go to BLOWER SWITCH TEST.

BLOWER MOTOR RESISTOR TEST ("A", "F", "J" & "N" BODY)

1. With blower motor resistor connected, ignition ON and blower switch on LO, measure voltage between Yellow wire and ground. If battery voltage is present, replace blower resistor assembly. If voltage is not present, check Yellow and Tan wires for an open.
2. With blower motor resistor connected, ignition ON and blower switch on MED, measure voltage between Light Blue wire and ground. If battery voltage is present, replace blower resistor assembly. If voltage is not present, check Light Blue wire for an open circuit.
3. With blower motor resistor connected, ignition ON and blower switch on HI, measure voltage between Orange wire and ground. If battery voltage is present, replace blower resistor assembly. If voltage is not present, check Orange wire for an open.

BLOWER MOTOR RESISTOR TEST ("L" BODY)

1. With blower motor resistor disconnected, ignition ON and blower switch at "1", measure voltage between Yellow wire and ground. If battery voltage is present, replace blower resistor assembly. If voltage is not present, check Yellow wire for an open circuit.
2. With blower motor resistor disconnected, ignition ON and blower switch at "2", measure voltage between Tan wire and ground. If battery voltage is present, replace blower resistor assembly. If voltage is not present, check Tan wire for an open circuit.
3. With blower motor resistor disconnected, ignition ON and blower switch at "3", measure voltage between Light Blue wire and ground. If battery voltage is read, replace blower resistor assembly. If voltage is not present, check Light Blue wire for an open circuit.
4. With blower motor resistor disconnected, ignition ON and blower switch at "3", measure voltage between Light Blue and Brown wires. If battery voltage is read, go to HEATER BLOWER RELAY TEST.

BLOWER MOTOR RESISTOR TEST ("W" BODY)

1. Disconnect blower motor resistor. Measure blower motor resistor resistance between Yellow and Purple/White wire terminals. If reading is 0.5-2.5 ohms, go to next step. If reading is not as specified, replace blower motor resistor.
2. Measure blower motor resistor resistance between Light Blue and Purple/White wire terminals. If reading is 0.1-1.2 ohms, go to next step. If reading is not as specified, replace blower motor resistor.
3. Measure blower motor resistor resistance between Light Blue and Dark Blue wire terminals. If reading is 0.5-2.5 ohms, blower motor resistor is okay. If reading is not as specified, replace blower motor resistor.

BLOWER SWITCH TEST ("A", "F", "J" & "N" BODY)

1. With blower switch connected and ignition switch in RUN position, measure voltage between Yellow wire and ground. If voltage is present, go to next step. If voltage is not present, check Brown and Yellow wires for an open circuit.
2. With blower switch connected, ignition switch in RUN position and blower switch on LO, measure voltage between Tan wire and ground. If voltage is present, go to next step. If voltage is not present, replace blower motor.
3. With blower switch connected, ignition switch in RUN position and blower switch on MED, measure voltage between Light Blue wire and ground. If voltage is present, go to next step. If voltage is not present, replace blower motor.
4. With blower switch connected, ignition switch in RUN position and blower switch on HI, measure voltage between Orange wire and ground. If voltage is present, go to next step. If voltage is not present, replace blower motor.

BLOWER SWITCH TEST ("L" BODY)

1. With blower switch connected and ignition switch in RUN position, measure voltage between Brown wire and ground. If voltage is present, go to next step. If voltage is not present, check Brown wire for an open circuit.
2. With blower switch connected and ignition switch in RUN position, measure voltage between Yellow wire and ground. If voltage is present, go to next step. If voltage is not present, replace blower motor.
3. With blower switch connected and ignition switch in RUN position, measure voltage between Tan wire and ground. If voltage is present, go to next step. If voltage is not present, replace blower motor.
4. With blower switch connected and ignition switch in RUN position, measure voltage between Light Blue wire and ground. If voltage is present, go to next step. If voltage is not present, replace blower motor.
5. With blower switch connected and ignition switch in RUN position, measure voltage between Orange wire and ground. If voltage is present, go to next step. If voltage is not present, replace blower motor.

BLOWER SWITCH TEST ("W" BODY)

1. Disconnect blower motor resistor. Place ignition switch in RUN position, blower switch on LO, and heater in VENT mode. Measure voltage between Yellow wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Yellow wire for an open circuit.
2. Measure voltage between Purple/White wire and ground. If voltage is zero, go to next step. If voltage is not zero, replace blower switch.
3. Place blower switch to M1 position (next to LO setting). Measure voltage between Purple/White wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Purple/white wire for an open circuit. If wire is okay, replace blower switch. If voltage was present in Yellow wire but not in Purple/White wire, check Yellow wire between low speed blower relay and blower switch.
4. Measure voltage between Light Blue wire and ground. If voltage is zero, go to next step. If voltage is other than zero, replace blower switch.
5. Place blower switch to M2 position (next to HI setting). Measure voltage between Light Blue wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Light Blue wire for an open circuit. If wire is okay, replace blower switch. If voltage was present in Yellow wire but not in Light Blue wire, check Yellow wire between low speed blower relay and blower switch.
6. Disconnect high speed blower relay (on convenience center). Place ignition switch in RUN position, blower switch on mid-two position, and heater in VENT mode. Measure voltage between Orange wire and ground. If voltage is zero, go to next step. If voltage is not zero, check Orange wire for a short circuit to voltage source. If wire is okay, replace blower switch.
7. Place blower switch on HI. Measure voltage between Orange wire and ground. If battery voltage is present, blower switch is operating properly. If battery voltage is not present, check Orange wire for a short circuit. If wire is okay, replace blower switch.

HEATER CONTROL ASSY BLOWER CONTROL TEST ("W" BODY)

1. Disconnect heater control (panel) assembly and place ignition switch in RUN position. Measure voltage between Pink/Black wire (C2 connector) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Pink/Black wire for an open circuit back to instrument cluster fuse.
2. Measure voltage between Pink/Black wire (C2 connector) and Yellow wire (C1 connector). If battery voltage is present, replace heater control (panel) assembly. If battery voltage is not present, go to LOW SPEED BLOWER RELAY TEST.

SOLENOID BOX TEST ("W" BODY)

1. Disconnect solenoid box and place ignition switch in RUN position. Measure voltage between Pink/White wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Pink/White wire for an open circuit. If wire is okay, check A/C fuse No. 1.
2. Disconnect heater control (panel) assembly, reconnect solenoid box, and place ignition switch in RUN position. Measure voltage between Purple wire (C2 connector) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Purple wire for an open circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace solenoid box.
3. Measure voltage between Red wire (C2 connector) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Red wire for an open circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace solenoid box.
4. Measure voltage between Light Green/Black wire (C2 connector) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Light Green/Black wire for an open circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace solenoid box.
5. Measure voltage between Tan wire (C1 connector) and ground. If battery voltage is present, go to HEATER CONTROL ASSEMBLY SOLENOID CONTROL TEST. If battery voltage is not present, check Tan wire for an open circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace solenoid box.

HEATER CONTROL ASSEMBLY SOLENOID TEST ("W" BODY)

1. Disconnect heater control (panel) assembly (C1 and C2 connectors). Place ignition switch in RUN position, solenoid box connected, and heater in all modes. Measure voltage between Pink/Black wire (C2 connector) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check instrument cluster fuse and Pink/Black wire for an open circuit.
2. Measure voltage between Pink/Black wire (C2 connector) and Black ground wire (C1 connector). If battery voltage is present, go to next step. If battery voltage is not present, check Black ground wire for an open circuit. Ensure ground connections are clean and tight.
3. Place heater in any mode except DEFROST. Measure voltage between Light Green/Black wire (C2 connector) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Light Green/Black wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.
4. Place heater in DEFROST mode. Measure voltage between Light Green/Black wire and ground. If voltage is less than 1.5 volts, go to next step. If voltage is not less than 1.5 volts, check Light Green/Black wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.
5. Measure voltage between Red wire (C2 connector) and ground with heater in OFF, VENT and HEAT mode. If voltage is less than 1.5 volts, go to next step. If voltage is not less than 1.5 volts, check Red wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.
6. Measure voltage between Red wire and ground with heater in BI-LEVEL, BLEND and DEFROST mode. If battery voltage is present, go to next step. If battery voltage is not present, check Red wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.
7. Place heater in VENT mode. Measure voltage between Tan wire (C1 connector) and ground. If voltage is less than 1.5 volts, go to next step. If voltage is not less than 1.5 volts, check Tan wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.
8. Place heater in any mode except VENT. Measure voltage between Tan wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Tan wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.
9. Measure voltage between Purple wire (C2 connector) and ground with heater in VENT and BI-LEVEL mode. If voltage is less than 1.5 volts, go to next step. If voltage is not less than 1.5 volts, check Purple wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.
10. Measure voltage between Purple wire and ground with heater in OFF, HEAT, BLEND and DEFROST mode. If battery voltage is present, but one or more air valves do not operate, check that valves move freely. Ensure actuator receives vacuum in proper modes. If no vacuum is present, replace solenoid box.
11. If battery voltage was NOT present in step 10), check Purple wire for an open/short circuit between heater control (panel) assembly and solenoid box. If wire is okay, replace heater control (panel) assembly.

AIR TEMP VALVE MOTOR TEST ("W" BODY)

1. Disconnect air temperature valve motor. Place ignition switch in RUN position, temperature lever in COLD, and heater in VENT mode. Measure voltage between Pink/Black wire and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Pink/Black wire for an open circuit.
2. Measure voltage between Pink/Black wire and Black ground wire. If battery voltage is present, go to next step. If battery voltage is not present, check Black wire for an open circuit.
3. Measure voltage between Light Blue wire and ground. If voltage is less than 2.0 volts, go to next step. If voltage is not less than 2.0 volts, check Light Blue wire for an open circuit. If wire is okay, go to step 5).
4. Place temperature lever in HOT. Measure voltage between Light Blue wire and ground. If battery voltage is present, but the valve does not move through its full range, check that valve moves freely. If valves is okay, replace air temperature valve motor. If battery voltage is not present, check Light Blue wire for an open circuit.
5. Ensure heater control (panel) assembly is connected. Place ignition switch in RUN position, temperature lever in HOT, and heater in VENT mode. Measure voltage between Light Blue wire (C1 connector) and ground. If battery voltage is present, go to next step. If battery voltage is not present, replace heater control (panel) assembly.
6. Place temperature lever in COLD. Measure voltage between Light Blue wire (C1 connector) and ground. If voltage is less than 2.0 volts, check that connectors on heater control (panel) assembly and air temperature valve motor are firmly seated. If voltage is incorrect, replace heater control (panel) assembly.

HEATER CONTROL PANEL ASSEMBLY R & I ("A" BODY)

Note. Before removal, mark any vacuum and electrical connections for reference during installation.

Disconnect battery negative cable. Remove instrument panel trim plate. Remove control panel retaining screws. Pull heater control panel out of instrument panel. Disconnect electrical connectors and control cables. (Scheme 3) To install, reverse removal procedure.

Scheme 3

HEATER CONTROL PANEL ASSEMBLY R & I ("F" BODY)

Disconnect battery negative cable. Remove trim plate from around heater control and radio. Remove screws retaining control panel to console and pull heater control out so cables and electrical connectors can be disconnected. (Scheme 4) To install, reverse removal procedure.

Scheme 4

HEATER CONTROL PANEL ASSEMBLY R & I ("J" BODY)

Disconnect battery negative cable. Remove heater control panel trim plate and attaching screws. Pull heater control out. Disconnect electrical connections and cables from heater control. (Scheme 5) To install, reverse removal procedure.

Scheme 5

HEATER CONTROL PANEL ASSEMBLY R & I ("L" BODY)

1. Disconnect negative battery cable. Disconnect cables at module. Remove control panel trim plate, control panel screws, and pull control panel out.
2. Disconnect cables from control panel. Disconnect electrical connection at control panel. To install, reverse removal procedure.

Scheme 6

HEATER CONTROL PANEL ASSEMBLY R & I ("N" BODY)

Disconnect negative battery cable. Remove trim plate. Remove center console extension. Remove control panel mounting screws. Disconnect electrical and vacuum connectors. Remove control panel. (Scheme 5) To install, reverse removal procedure.

HEATER CONTROL PANEL ASSEMBLY R & I ("W" BODY)

Disconnect negative battery cable. Remove trim plate. Remove screws securing assembly and remove assembly from dash. Disconnect electrical connections from assembly. To install, reverse removal procedure.

HEATER CORE R & I ("A" BODY)

1. Drain cooling system. Remove instrument panel lower sound absorber. Disconnect coolant hoses at heater core. Remove heater duct and heater case side cover.
2. Remove heater lower outlet. Remove 2 housing cover to air valve housing clips. Remove core retaining straps. Remove core tubing retainers and heater core. To install, reverse removal procedure. Fill cooling system.

HEATER CORE R & I ("F" BODY)

1. Disconnect battery negative cable. Drain radiator. Disconnect heater hoses. Plug hoses and heater core tubes. Remove lower right sound panel and lower right instrument trim panel.
2. Remove screw from lower right instrument panel carrier to cowl. Remove heater case cover screws and remove cover. Remove screws from support plate and heater core. Remove heater core with support plate. To install, reverse removal procedure. Fill cooling system.

HEATER CORE R & I ("L" BODY)

Drain cooling system. Remove heater inlet and outlet hoses from heater core. Remove heater outlet deflector. Remove heater core cover. Remove heater core retaining straps and remove heater core. To install, reverse removal procedure. Fill cooling system.

HEATER CORE R & I ("J", "N" BODY)

Drain cooling system. Raise and support vehicle. From underneath vehicle, remove heater hoses from heater core. Remove drain tube. Lower vehicle. Remove right and left side insulator panel. Lower heating duct and hoses. Remove heater core cover and remove heater core. To install, reverse removal procedure. Fill cooling system.

Scheme 7

1. Drain cooling system. Place transaxle in Neutral and disconnect battery cable. Move coolant reservoir out of way (DO NOT remove hoses). Disconnect torque strut-to-engine bracket nut and bolt. Using a pry bar at engine torque strut bracket, rotate engine/transaxle assembly forward. Align slave hole in torque strut with engine bracket hole. Retain engine in this position, using torque strut-to-engine bracket bolt. (Scheme 7)
2. Remove heater hose retaining bracket nuts and heater hoses from core. Lower right sound insulator panel, rear seat duct adapter, heater floor duct and then lower left sound insulator panel. Remove core cover screws and cover. Remove core retaining bolt and core. To install, reverse removal procedure. Fill cooling system.

BLOWER MOTOR R & I EXCEPT ("W" BODY)

1. Disconnect battery negative cable. Disconnect electrical wires at blower motor. Remove blower motor cooling tube on "F" body or plastic water shield from right side of cowl on "J" body. On "N" body, remove drive belt and 2 power steering mounting bolts.
2. On all models, scribe reference marks from blower motor to housing position. Remove retaining screws and remove blower motor with fan. Pry flange away from housing (if necessary) and remove blower assembly. To install, reverse removal procedure. Replace sealing material at motor flange if necessary. Ensure reference marks are aligned.

BLOWER MOTOR R & I ("W" BODY)

Disconnect battery negative cable. Remove right sound insulator panel. Loosen front screw and remove rear screws from electrical convenience center. Slide convenience center out. Disconnect electrical connector at motor. Remove harness from clip and blower motor mounting screws. Remove blower motor. To install, reverse removal procedure.

Heater Wiring Diagram (Beretta & Corsica). Scheme 8

Heater Wiring Diagram (Camaro & Firebird). Scheme 9

Heater Wiring Diagram (Cavalier). Scheme 10

Heater Wiring Diagram (Cutlass Calais, Cutlass Ciera, Cutlass Cruiser, Grand Am, Sunbird & 6000). Scheme 11

Heater Wiring Diagram (Skylark). Scheme 12

Heater Wiring Diagram (Lumina). Scheme 13