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Heater System: Other Chevrolet Prizm I

Heater 2 illustrations ~2102 words

Ventilation

Airflow is discharged from upper instrument panel outlets. Quantity of airflow is controlled by blower speed setting and vehicle speed.

Bi-Level

Airflow is discharged from upper instrument panel outlets and floor outlets. Airflow from floor outlets is warmer than airflow from upper instrument panel outlets.

Most of the of airflow is discharged from floor outlets, with a small amount being delivered to windshield defrost and side window outlets.

Heat/Defrost

Most of the airflow is delivered to floor outlets and windshield defrost outlets, with the remaining being delivered to the side window outlets.

Defrost

Airflow is discharged from windshield defrost outlets. A small amount is delivered to side window and floor outlets.

FRESH/RECIRCULATED AIR CONTROL LEVER

The fresh/recirculated air control lever mechanically operates a cable which opens or closes the fresh/recirculation mode door to fresh (outside) air. When fresh/recirculated air control lever is set to fresh, outside air is delivered to vehicle interior. With lever in fresh mode, as vehicle speed increases, in addition to blower motor speeds, airflow through system increases. When lever is in recirculation position, outside air is shut off and air from inside passenger compartment is recirculated through the blower motor to selected air outlets. (Scheme 4)

Scheme 4

Scheme 4: FRESH/RECIRCULATED AIR CONTROL LEVER
Scheme 4: FRESH/RECIRCULATED AIR CONTROL LEVER

BLOWER SPEED SELECTOR SWITCH

The blower speed selector switch operates blower motor at one of 4 speeds, OFF, LO, medium-low (M1), medium-high (M2) and HI. (Scheme 4)

TEMPERATURE CONTROL KNOB

When temperature control knob is moved to full hot position air mix door opens fully, allowing all airflow to be routed through heater core to selected outlets. In full cold position, air mix door closes off airflow through heater core. Adjusting air temperature control knob allows more or less air to by-pass heater core.

The temperature control knob also controls the engine coolant control valve which controls the amount of engine coolant allowed to pass through the heater core. When knob is turned to the full cool position, the engine coolant control valve is closed.

TEMPERATURE CONTROL CABLE

Remove knee bolster, glove box and center console. Remove radio from instrument panel. Disconnect temperature control cable from clip and air mix door lever at heater case. Set temperature control knob to full cold position. At heater case, push air mix door lever away from cable (clockwise). Attach cable to lever and cable housing with cable clip. Check temperature control knob for smooth operation and make sure that it stops in correct spots.

MODE CONTROL CABLE

Remove knee bolster. Disconnect mode control cable from clip and mode control lever at heater case. Set mode knob to defrost position. At heater case, move mode control lever toward cable and housing (counterclockwise). Attach cable to mode control lever and cable housing with cable clip. Check mode knob for smooth operation and make sure that it stops in correct spots. Reinstall knee bolster.

FRESH/RECIRCULATED AIR CONTROL CABLE

Remove glove box. Disconnect fresh/recirculated air control cable from clip and air inlet door at blower case. Set fresh/recirculated air control lever to recirculated air position. At blower case move door lever toward fresh/recirculated air cable (counterclockwise). Attach cable to air control lever and cable housing with cable clip. Check fresh/recirculated air control lever for smooth operation and make sure that it stops in correct spots. Reinstall glove box.

BLOWER CONTROL SYSTEM CHECK

Turn ignition switch to ON position. Move blower speed selector switch from low to high positions and listen for increase in blower motor speed at each switch position. Move blower speed selector switch from high to low positions and listen for decrease in blower motor speed. If blower motor is inoperative in any or all speeds, go to appropriate diagnostic procedure.

Scheme 5

Scheme 5: BLOWER MOTOR INOPERATIVE AT ANY SPEED
Scheme 5: BLOWER MOTOR INOPERATIVE AT ANY SPEED
  1. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000). Go to next step.
  2. Disconnect blower motor connector. Connect test light between blower motor connector terminals. Start engine. Set blower selector switch to any position except OFF. If test light comes on, go to step 14. If test light does not come on, go to next step.
  3. Check for open in Black/White wire between blower motor and blower motor resistor. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000). If circuit is okay, go to next step. If circuit is not okay, go to step 16.
  4. Check for open in Black wire between blower motor and heater relay cavity terminal No. 4. Heater relay is located in fuse/relay block No. 3, in right front of engine compartment, on radiator support. If circuit is okay, go to next step. If circuit is not okay, go to step 15.
  5. Remove heater relay. Check for continuity across specified relay terminals. See «HEATER RELAY TEST»(ref-245-S19936972312000030800000). If relay tests okay, go to next step. If relay does not test okay, go to step 13. HEATER RELAY TEST Terminals No. Continuity 4 & 5 No 4 & 2 Yes
  6. With heater relay removed, use a DVOM to measure voltage between ground and heater relay cavity terminal No. 1. If battery voltage is indicated, go to step 8. If battery voltage is not indicated, go to next step.
  7. Check for open in Red/Blue wire between fuse/relay block No. 3 and multifunction alarm module, including junction block No. 3. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000). If circuit is okay, go to step 17. If circuit is not okay, go to step 15.
  8. Turn engine off. Install heater relay. Disconnect blower speed selector switch. Start engine. Connect DVOM between ground and blower speed selector switch connector terminal No. 3 (Blue/Orange wire). If battery voltage is indicated, go to next step. If battery voltage is not indicated, go to step 10.
  9. Check for open in White/Black wire between blower speed selector switch connector terminal No. 1 and ground. If circuit is okay, go to step 11. If circuit is not okay, go to step 15.
  10. Check for open in Blue/Orange wire between fuse and relay box No. 3 and blower speed selector switch connector terminal No. 3. If circuit is okay, go to step 15. If circuit is not okay, go to step 13.
  11. Turn engine off. Ensure blower speed selector switch is disconnected. Check for continuity between specified terminals and at specific switch positions. See «BLOWER SPEED SELECTOR SWITCH TEST»(ref-245-S20496170682000030800000) table. If switch tests okay, go to step 13. If switch does not test okay, go to next step. BLOWER SPEED SELECTOR SWITCH TEST Switch Position (1) Terminals No. Continuity All 1 & 3 Yes Medium-Low (M1) 3 & 4 Yes Medium-High (M2) 3 & 8 Yes HI 3 & 5 Yes (1) (Scheme 5)
  12. Replace blower speed selector switch. See «BLOWER SPEED SELECTOR SWITCH»(ref-245-S24706174222000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000).
  13. Replace heater relay. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000).
  14. Replace blower motor. See «BLOWER MOTOR & FAN»(ref-245-S08066273032000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000).
  15. Repair open in suspect circuit. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000).
  16. Repair open in Black/White wire between blower motor and splice S200. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000). Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000).
  17. Replace multifunction alarm module. See «MULTIFUNCTION ALARM MODULE»(ref-245-S38917016952000030800000) under REMOVAL & INSTALLATION.

BLOWER MOTOR OPERATES ONLY IN HIGH POSITION

  1. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) . Go to next step.
  2. Check for open in Black/White wire between blower motor and blower motor resistor terminal No. 4. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . If circuit is okay, go to next step. If circuit is not okay, go to step 6 .
  3. Turn ignition switch to OFF position. Disconnect blower speed selector switch. Use a DVOM to test switch continuity between specified terminals with switch in medium-low (M1) and medium-high (M2) positions. See «BLOWER SPEED SELECTOR SWITCH TEST»(ref-245-S20496170682000030800000) table. If switch tests okay, go to step 5 . If switch does not test okay, go to next step.
  4. Replace blower speed selector switch. See «BLOWER SPEED SELECTOR SWITCH»(ref-245-S24706174222000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  5. Replace blower motor resistor. See «BLOWER MOTOR RESISTOR»(ref-245-S41296594002000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  6. Repair open in Black/White wire between blower motor and splice S200. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .

BLOWER MOTOR DOES NOT OPERATE IN HIGH POSITION

  1. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) . Go to next step.
  2. Check for open in Black/White wire between blower speed selector switch and splice S200. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . If circuit is okay, go to next step. If circuit is not okay, go to step 4 .
  3. Replace blower speed selector switch. See «BLOWER SPEED SELECTOR SWITCH»(ref-245-S24706174222000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  4. Repair open in Black/White wire between blower speed selector switch and splice S200. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .

BLOWER MOTOR DOES NOT OPERATE IN MEDIUM-HIGH POSITION

  1. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) . Go to next step.
  2. Turn ignition switch to OFF position. Disconnect blower speed selector switch. Use a DVOM to test switch continuity between specified terminals with switch in medium-high (M2) position. See «BLOWER SPEED SELECTOR SWITCH TEST»(ref-245-S20496170682000030800000) table. If switch tests okay, go to step 5 . If switch does not test okay, go to next step.
  3. Check for open in Blue/Black wire between blower speed selector switch terminal No. 8 and blower motor resistor connector terminal No. 3. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . If circuit is okay, go to next step. If circuit is not okay, go to step 6 .
  4. Replace blower motor resistor. See «BLOWER MOTOR RESISTOR»(ref-245-S41296594002000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  5. Replace blower speed selector switch. See «BLOWER SPEED SELECTOR SWITCH»(ref-245-S24706174222000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  6. Repair open in Blue/Black wire between blower speed selector switch and blower motor resistor. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .

BLOWER MOTOR DOES NOT OPERATE IN MEDIUM-LOW POSITION

  1. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) . Go to next step.
  2. Turn ignition switch to OFF position. Disconnect blower speed selector switch. Use a DVOM to test switch continuity between specified terminals with switch in medium-low (M1) position. See «BLOWER SPEED SELECTOR SWITCH TEST»(ref-245-S20496170682000030800000) table. If switch tests okay, go to step 5 . If switch does not test okay, go to next step.
  3. Check for open in Red wire between blower speed selector switch terminal No. 4 and blower motor resistor connector terminal No. 3. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . If circuit is okay, go to next step. If circuit is not okay, go to step 6 .
  4. Replace blower motor resistor. See «BLOWER MOTOR RESISTOR»(ref-245-S41296594002000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  5. Replace blower speed selector switch. See «BLOWER SPEED SELECTOR SWITCH»(ref-245-S24706174222000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  6. Repair open in Blue/Black wire between blower speed selector switch and blower motor resistor. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .

BLOWER MOTOR DOES NOT OPERATE IN LOW POSITION

  1. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) . Go to next step.
  2. Check for open in White/Black wire between blower motor resistor terminal No. 1 and ground. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . If circuit is okay, go to next step. If circuit is not okay, go to step 4 .
  3. Replace blower motor resistor. See «BLOWER MOTOR RESISTOR»(ref-245-S41296594002000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  4. Repair open in White/Black wire between blower motor resistor terminal No. 1 and ground. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .

BLOWER MOTOR OPERATES IN OFF POSITION

  1. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) . Go to next step.
  2. Remove heater relay from fuse/relay block No. 3. Fuse/relay block No. 3 is located in right front of engine compartment. Turn ignition switch to ON position. If blower motor runs, go to next step. If blower motor does not run, go to step 4 .
  3. Repair short to voltage in Black wire between fuse/relay block No. 3 and blower motor. See «WIRING DIAGRAMS»(ref-245-S07586982912000030800000) . Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  4. Test heater relay. See «HEATER RELAY TEST»(ref-245-S19936972312000030800000) . If heater relay is okay, go to next step. If heater relay is not okay, go to step 6 .
  5. Turn blower speed selector switch to OFF position. Check for short to ground in Blue/Orange wire between blower speed selector switch connector terminal No. 3 and fuse/relay block No. 3. If circuit is not okay, go to step 7 . If circuit is okay, go to step 8 .
  6. Replace heater relay. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  7. Repair short to ground in Blue/Orange wire between blower speed selector switch connector terminal No. 3 and fuse/relay block No. 3. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .
  8. Replace blower speed selector switch. See «BLOWER SPEED SELECTOR SWITCH»(ref-245-S24706174222000030800000) under REMOVAL & INSTALLATION. Perform «BLOWER CONTROL SYSTEM CHECK»(ref-245-S29677880642000030800000) .

CONTROL CABLES

Note. Notice routing of control cables, prior to removal, to prevent binding after installation.

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