BLOWER SWITCH
Switch controls blower motor speed through blower resistor. Blower speed is adjusted by control lever or knob.
CONTROL PANEL
Temperature and mode knobs or levers are connected by cable to heater coolant valve and air doors. Fresh/recirculation lever provides choice of outside air or recirculated inside air.
HEATER RELAY
A heater (or main) relay controls current through system. For location of heater (main) relay, see WIRING DIAGRAMS .
BLOWER MOTOR DOES NOT WORK
Check for blown heater fuse or faulty heater relay. Inspect heater blower motor switch, heater blower motor resistor, heater blower motor, or faulty wiring. See WIRING DIAGRAMS .
INCORRECT TEMPERATURE OUTPUT
Check for broken or out of adjustment control cables, heater hoses leaking or clogged, or faulty water pump. Inspect for broken air dampers, clogged air ducts, leaking or clogged heater core, or faulty heater control unit.
NO TEMPERATURE CONTROL
Check for proper engine coolant level. Check for faulty water valve. Check heater control panel.
NO WARM AIR OUTPUT
Check for proper engine coolant level. Check for faulty water valve. Check heater control panel. Check for leaking or clogged heater core.
COMPONENT TESTS
| WARNING | To avoid injury from accidental air bag deployment, read and carefully follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. |
BLOWER MOTOR
Disconnect blower motor harness connector. To identify blower motor terminals, see WIRING DIAGRAMS . Replace motor if it does not operate smoothly. Perform the following test procedures
RAV4, Tacoma & Tundra
Apply battery voltage to motor terminal No. 1 and ground terminal No. 2.
4Runner (Front Blower)
Apply battery voltage to motor terminal No. 2 and ground terminal No. 1.
4Runner (Rear Blower)
Apply battery voltage to motor terminal No. 1 and ground terminal No. 2.
BLOWER MOTOR RESISTOR
Note. On some vehicles, it may be necessary to remove blower motor resistor before testing it.
- Disconnect blower motor resistor harness connector. (Scheme 15) See «WIRING DIAGRAMS»(ref-98908-S39764436842001060500000). Check for continuity between blower motor resistor terminals No. 1, 2, 3 and 4. If continuity exists between all terminals, go to next step. If continuity does not exist between any terminals, replace blower motor resistor.
- Using DVOM, measure resistance between indicated terminals. (Scheme 15) See «WIRING DIAGRAMS»(ref-98908-S39764436842001060500000). See «BLOWER MOTOR RESISTOR (EXCEPT 4RUNNER)»(ref-98908-S15868409962001072700000) table. If resistance is not as specified, replace blower motor resistor.
| Terminals No. | Ohms | |
|---|---|---|
| RAV4 | ||
| 1 & 3 | 0.4 | |
| 1 & 4 | 2.8 | |
| 2 & 3 | 0.7 | |
| Tacoma | ||
| 1 & 2 | 1.6-2.0 | |
| 1 & 3 | 1.0-1.4 | |
| 1 & 4 | 2.1-2.3 | |
| Tundra | ||
| 1 & 2 | 2.7-3.1 | |
| 1 & 3 | 1.8-2.0 | |
| 1 & 4 | 3.1-3.5 | |
BLOWER MOTOR RESISTOR (EXCEPT 4RUNNER)
4Runner (Front)
Disconnect blower motor resistor harness connector. Using a DVOM, measure resistance between indicated terminals. (Scheme 15) See WIRING DIAGRAMS. See BLOWER MOTOR RESISTOR (4RUNNER) table. If resistance is as specified, blower motor resistor is okay. If resistance is not as specified, replace blower motor resistor.
| Terminals No. | Ohms | |
|---|---|---|
| Front | ||
| 1 & 2 | 1.6-2.0 | |
| 1 & 3 | 1.0-1.4 | |
| 1 & 4 | 2.1-2.3 | |
| Rear | ||
| 1 & 2 | 3.0-3.4 | |
BLOWER MOTOR RESISTOR (4RUNNER)
Scheme 15
4Runner (Rear)
Disconnect rear blower motor resistor harness connector. Using a DVOM, measure resistance between indicated terminals. (Scheme 16) See WIRING DIAGRAMS. See BLOWER MOTOR RESISTOR (4RUNNER) table. If resistance is as specified, rear blower motor resistor is okay. If resistance is not as specified, replace rear blower motor resistor.
Scheme 16
Front
Disconnect harness connector from blower speed control switch. With switch in indicated position, check for continuity between specified terminals. See FRONT BLOWER SPEED CONTROL SWITCH table. (Scheme 17)or (Scheme 18). If continuity is not as specified, replace blower speed control switch.
| Switch Position | (1) Continuity Between Terminals No. | |
|---|---|---|
| RAV4 & 4Runner | ||
| OFF | (1) | |
| LO | 5 & 6 | |
| (D) (2) | 1, 5 & 6 | |
| (D) (3) | 2, 5 & 6 | |
| HI | 5, 6 & 8 | |
| Tacoma | ||
| OFF | (1) | |
| LO | 1 & 8 | |
| (D) (2) | 1, 3 & 8 | |
| (D) (3) | 1, 2 & 8 | |
| HI | 1, 6 & 8 | |
| Tundra | ||
| OFF | (1) | |
| LO | 1 & 3 | |
| M1 | 1, 3 & 4 | |
| M2 | 1, 3 & 8 | |
| HI | 1, 3 & 5 | |
| (1) With switch in any position, continuity should exist between terminals No. 3 and 4. With switch in OFF position, continuity should not exist between any other terminals. (2) Circle (D) closer to LO position. (3) Circle (D) closer to HI position. | ||
| (1) | With switch in any position, continuity should exist between terminals No. 3 and 4. With switch in OFF position, continuity should not exist between any other terminals. |
| (2) | Circle (D) closer to LO position. |
| (3) | Circle (D) closer to HI position. |
FRONT BLOWER SPEED CONTROL SWITCH
Scheme 17
Scheme 18
Rear
Disconnect harness connector from rear blower speed control switch. With switch in indicated position, check for continuity between specified terminals. See REAR BLOWER SPEED CONTROL SWITCH (4RUNNER) table. (Scheme 19) If continuity is not as specified, replace rear blower speed control switch.
| Switch Position | Continuity Between Terminals No. |
|---|---|
| OFF | (1) |
| LO | 2 & 3 |
| HI | 1, 2 & 3 |
| (1) No continuity between terminals. | |
| (1) | No continuity between terminals. |
REAR BLOWER SPEED CONTROL SWITCH (4RUNNER)
Scheme 19
- Disconnect negative battery cable. Remove relay. See «WIRING DIAGRAMS»(ref-98908-S39764436842001060500000). Using a DVOM, check for continuity between relay terminals No. 3 and 5, No. 2 and 4, and No. 1 and 2. (Scheme 20) If continuity exists between terminals No. 3 and 5 and No. 2 and 4, and does not exist between terminals No. 1 and 2, go to next step. If continuity does not exist between terminals No. 3 and 5 or No. 2 and 4, or exists between terminals No. 1 and 2, replace relay.
- Connect battery voltage to terminal No. 3 and ground terminal No. 5. Check for continuity between terminals No. 1 and 2 and No. 1 and 4. If continuity exists between terminals No. 1 and 2, relay is okay. If continuity does not exist between terminals No. 1 and 4, replace relay.
- Disconnect negative battery cable. Remove relay. See «WIRING DIAGRAMS»(ref-98908-S39764436842001060500000). Using a DVOM, check for continuity between relay terminals No. 3 and 5, No. 2 and 4, and No. 1 and 2. (Scheme 20) If continuity exists between terminals No. 3 and 5 and No. 2 and 4, and does not exist between terminals No. 1 and 2, go to next step. If continuity does not exist between terminals No. 3 and 5 or No. 2 and 4, or exists between terminals No. 1 and 4, replace relay.
- Connect battery voltage to terminal No. 3 and ground terminal No. 5. Check for continuity between terminals No. 1 and 2 and No. 1 and 4. If continuity exists between terminals No. 1 and 2, relay is okay. If continuity does not exist between terminals No. 1 and 4, replace relay.
- Disconnect negative battery cable. Remove relay. See «WIRING DIAGRAMS»(ref-98908-S39764436842001060500000). Using a DVOM, check for continuity between relay terminals No. 1 and 2, No. 3 and 4, and No. 3 and 5. (Scheme 21) If continuity exists between terminals No. 1 and 2 and No. 3 and 4, and does not exist between terminals No. 3 and 5, go to next step. If continuity does not exist between terminals No. 1 and 2 or No. 3 and 4, or exists between terminals No. 3 and 5, replace relay.
- Connect battery voltage to terminal No. 1 and ground terminal No. 2. Check for continuity between terminals No. 3 and 5. If continuity exists between terminals No. 3 and 5, relay is okay. If continuity does not exist between terminals No. 3 and 5, replace relay.
Scheme 20
Scheme 21
INSTRUMENT PANEL
Note. Instrument panel removal and installation procedure may vary slightly depending upon model application.