TROUBLE SHOOTING
Verify customers concern by operating system (if possible). Visually inspect for obvious signs of mechanical or electrical damage. Check for blown fuses, loose or damaged wires and connectors or faulty blower motor. Check for damaged or misrouted vacuum hoses and broken or leaking vacuum control motor(s). If fault is not evident, diagnose problem by symptom. See SYMPTOM TESTS .
SYMPTOM TESTS
| Symptom | Test |
|---|---|
| Incorrect/Erratic Direction Of Airflow From Outlet | A |
| Insufficient, Erratic, Or No Heat | B |
| No Operation In All Temperature Settings | F |
| The Blower Motor Is Inoperative/Does Not Operate Correctly | G |
| The Blower Motor Operates Continuously In High Speed | H |
| No Operation In High Blower Setting | I |
| No Operation In Lower Blower Setting | J |
SYMPTOM TEST DIRECTORY
TEST A: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET
Note. For circuit reference, see WIRING DIAGRAMS .
Diagnostic Procedure
For testing procedure (Scheme 2)- (Scheme 13).
Scheme 2
Scheme 3
Scheme 4
Scheme 5
Scheme 6
Scheme 7
Scheme 8
Scheme 9
Scheme 10
Scheme 11
Scheme 12
Scheme 13
TEST B: INSUFFICIENT, ERRATIC, OR NO HEAT
Note. For circuit reference, see WIRING DIAGRAMS .
For testing procedure (Scheme 14)- (Scheme 16).
Scheme 14
Scheme 15
Scheme 16
For testing procedure (Scheme 17)- (Scheme 19).
Scheme 17
Scheme 18
Scheme 19
TEST G: BLOWER MOTOR IS INOPERATIVE/DOES NOT OPERATE CORRECTLY
Note. For circuit reference, see WIRING DIAGRAMS .
For testing procedure (Scheme 20)- (Scheme 24).
Scheme 20
Scheme 21
Scheme 22
Scheme 23
Scheme 24
TEST H: BLOWER MOTOR OPERATES CONTINUOUSLY IN HIGH SPEED
Note. For circuit reference, see WIRING DIAGRAMS .
For testing procedure (Scheme 25)- (Scheme 27).
Scheme 25
Scheme 26
Scheme 27
For testing procedure (Scheme 28)and (Scheme 29).
Scheme 28
Scheme 29
For testing procedure (Scheme 30)- (Scheme 33).
Scheme 30
Scheme 31
Scheme 32
Scheme 33
Plug Test
Check for proper coolant level. Start engine and turn heater on. When engine reaches normal operating temperature, feel heater outlet hose. It should be hot. If outlet hose is not hot, heater core may have an air pocket, may be plugged, or thermostat may not be working properly. If outlet hose is hot, perform appropriate pressure test.
Pressure Test (On Vehicle)
- Drain cooling system. Disconnect heater hoses from heater core. Install a short piece of heater water hose, about 4" (101 mm) long, on each heater core tube. (Scheme 34)
- Fill heater core and heater hoses with water. Install Plug (BT-7422-B) on one hose end and Adapter (BT-7422-A) on other hose end. (Scheme 34) Secure hoses, plug, and adapter to hoses with hose clamps.
- Attach pump and gauge assembly from a radiator/heater core pressure tester to adapter fitting on heater hose. Close tester bleed valve and apply 35 psi (2.5 kg/cm 2 ) air pressure to heater core. Observe gauge for a minimum of 3 minutes.
- If pressure drops, check all hose clamp connections for proper fit; replace leaking hoses or clamps. If hoses do not leak, remove heater core from vehicle and perform bench test. See «PRESSURE TEST (BENCH)»(ref-151647-S31518967492003030500000).
Scheme 34
Pressure Test (Bench)
Note. Due to space limitations, a bench test may be necessary for pressure testing.
- Remove heater core from vehicle. See «HEATER CORE»(ref-151647-S15029273002003010600000) under REMOVAL & INSTALLATION.
- Drain all of coolant from heater core.
- Install a short piece of heater water hose, about 4" (101 mm) long, on each heater core tube. (Scheme 34)
- Install Plug (BT-7422-B) on one hose end and Adapter (BT-7422-A) on other hose end. (Scheme 34) Secure hoses, plug, and adapter to hoses with hose clamps. Attach pump and gauge assembly from a radiator/heater core pressure tester to adapter fitting on heater hose. Close tester bleed valve and apply 35 psi (2.5 kg/cm 2 ) air pressure to heater core.
- Submerge heater core in water. If a leak is observed, replace heater core.