Home ReviewsRefund
Home/Lexus/LS/Lexus LS I (1989-1994)/Repair manual/Cooling Fan/Engine Cooling Fans
Contents Section: Cooling Fan All sections

Engine Cooling Fans Lexus LS I

Cooling Fan 17 illustrations ~1021 words

DESCRIPTION & OPERATION

Engine cooling fan system consists of 2 electric fans and one mechanical fan. Mechanical cooling fan is temperature-controlled and operated in 3 stages. Air passing through the radiator gradually heats up the bi-metal component of the fan. Fluid stored in chambers inside cooling fan flows into operating chambers inside fan, causing fan motion to increase as temperature rises. (Scheme 16) Electric cooling fans are controlled by relays between engine, A/C system and a coolant temperature sensor. Primary electric fan is activated when coolant reaches 93°C and shuts off when coolant temperature drops below 83°C. Secondary electric fan is activated when A/C refrigerant pressure reaches a specified pressure to provide additional cooling for the engine.

ELECTRICAL COMPONENTS

For electrical component locations (Scheme 1)

Scheme 1

Scheme 1: ELECTRICAL COMPONENTS
Scheme 1: ELECTRICAL COMPONENTS

MECHANICAL COMPONENTS

For mechanical component locations (Scheme 2)

Scheme 2

Scheme 2: MECHANICAL COMPONENTS
Scheme 2: MECHANICAL COMPONENTS

A/C FAN OPERATION

For diagnosis and testing of A/C system control of cooling fans, see COOLING FAN SYSTEM under TESTING in AUTOMATIC A/C article.

Low Coolant Temperature (Below 83°C)

  1. Turn vehicle ignition ON. Fan should not rotate.
  2. If fan rotates, check for separated electrical connector or severed wire between relay and temperature switch.

High Coolant Temperature (Above 93°C)

  1. Start engine and run so coolant temperature reaches 93°C or higher. Cooling fan should rotate.
  2. If fan does not rotate, replace temperature switch.

Temperature Switch Connector

  1. Turn vehicle ignition ON.
  2. Disconnect temperature switch connector located on left side of radiator. (Scheme 3)
  3. Fan should rotate.
  4. If fan does not rotate, check fan relay, fan motor, ignition relay and fuse, and check for a short circuit between fan relay and temperature switch.

Scheme 3

Scheme 3
Scheme 3

Checking High Temperature Control (Above 93°C)

  1. Remove temperature switch from radiator. (Scheme 1)for location.
  2. Heat a pan of water to at least 93°C, but DO NOT boil water.
  3. Place tip of switch in water and check for continuity. (Scheme 4)
  4. No continuity should be present. If continuity is present, replace temperature switch.

Scheme 4

Scheme 4
Scheme 4

Checking Low Temperature Control (Below 83°C)

  1. Remove temperature switch from radiator. (Scheme 1)for switch location.
  2. Place tip of switch in water and check for continuity. (Scheme 4)
  3. Heat water slowly to 83°C. Check continuity of temperature switch as water temperature rises.
  4. Continuity should be present up to 83°C. If no continuity is present, replace temperature switch.

A/C HIGH PRESSURE SWITCH

For diagnosis and testing of A/C system control of cooling fans, see COOLING FAN SYSTEM under TESTING in AUTOMATIC A/C article.

Checking Relay Continuity

Procedure applies to both relays. Cooling fan relays are located in No. 6 Relay Block just behind driver-side headlight. (Scheme 1)

  1. Disconnect and remove cooling fan relay.
  2. Check for continuity between terminals No. 1 and 2. (Scheme 5)
  3. Check for continuity between terminals No. 3 and 4. (Scheme 5)
  4. If no continuity is present, replace relay.

Scheme 5

Scheme 5
Scheme 5

Checking Relay Operation

Procedure applies to both relays. Cooling fan relays are located in No. 6 Relay Block just behind driver-side headlight. (Scheme 1)

  1. Disconnect and remove cooling fan relay.
  2. Apply battery voltage across terminals No. 1 and 2. (Scheme 6)
  3. Check that there is NO continuity between terminals No. 3 and 4. (Scheme 6)
  4. If continuity is present, replace relay.

Scheme 6

Scheme 6
Scheme 6

No. 3 cooling fan relay is located in No. 6 Relay Block just behind driver-side headlight. Engine Main relay is located in No. 2 Junction Block located near driver-side shock absorber tower. (Scheme 1)

  1. Disconnect and remove relay.
  2. Check for continuity between terminals No. 1 and 3. If no continuity is present, replace relay. (Scheme 7)
  3. Check for continuity between terminals No. 2 and 4. If no continuity is present, replace relay. (Scheme 7)
  4. Check that there is NO continuity between terminals No. 4 and 5. If continuity is present, replace relay. (Scheme 7)

Scheme 7

Scheme 7
Scheme 7

No. 3 cooling fan relay is located in No. 6 Relay Block just behind driver-side headlight. Engine Main relay is located in No. 2 Junction Block located near driver-side shock absorber tower. (Scheme 1)

  1. Disconnect and remove relay.
  2. Apply battery voltage across terminals No. 1 and 3. (Scheme 8)
  3. Check for continuity between terminals No. 4 and 5. If no continuity is present, replace relay. (Scheme 8)
  4. Check that there is NO continuity between terminals No. 2 and 4. If continuity is present, replace relay. (Scheme 8)

Scheme 8

Scheme 8
Scheme 8

COOLING FAN MOTORS NO. 1 & 2

  1. Disconnect fan motor electrical connector.
  2. Connect battery and ammeter to fan motor connector. (Scheme 9)
  3. Check that fan motor rotates smoothly. Current should be 4.2-4.4 Amps.

Scheme 9

Scheme 9
Scheme 9

Removal & Installation

  1. Disconnect negative battery terminal. Wait at least 20 seconds before beginning work after disconnecting.
  2. Remove vehicle hood.
  3. Remove dust covers and air duct. (Scheme 10)
  4. Remove battery.
  5. Remove under-car covering.
  6. Drain engine oil.
  7. Drain engine coolant and disconnect upper radiator hose.
  8. Remove drive belt. See appropriate DRIVE BELT ROUTING article.
  9. Remove nuts (4) from around fan. Remove fan and fluid coupling assembly. (Scheme 11) To install, reverse removal procedure.

Scheme 10

Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11
  1. Remove headlights.
  2. Remove front bumper.
  3. Remove horns.
  4. Disconnect electrical plugs from fan motor connectors.
  5. Disconnect cooling fan wires from brackets.
  6. Remove each set of 3 bolts from both fans. Remove fans.
  7. To install, reverse removal procedure.

Note. (Scheme 12)for exploded view of front bumper assembly.

  1. Remove corner light. Remove screw, disconnect electrical plug and pull light out. Disconnect bulb from light.
  2. Remove headlights. Remove bolts (3) and slide headlight out with bracket. Disconnect electrical plugs.
  3. Remove cover from under engine.
  4. Remove lower wind guide. Disconnect tube and remove screws (7).
  5. Remove fender liner from bumper.
  6. Remove bumper and upper bumper retainer: Remove 2 nuts and retainer. Remove 2 bolts from bumper. Loosen clips and remove with a clip remover. Remove upper bumper retainer with clips. (Scheme 13) Disconnect light bulbs from bumper. If vehicle is equipped with headlight washers, disconnect hose from washer nozzle. Disconnect connection at both sides of bumper. Pull bumper forward to remove. Ensure that serrations on side bolts are not damaged. (Scheme 14)
  7. Remove bumper reinforcement. (Scheme 15)

Scheme 12

Scheme 12
Scheme 12

Scheme 13

Scheme 13
Scheme 13

Scheme 14

Scheme 14
Scheme 14

Scheme 15

Scheme 15
Scheme 15

Scheme 16

Scheme 16: MECHANICAL COOLING FAN
Scheme 16: MECHANICAL COOLING FAN

Electric Cooling Fan Wiring Diagram. Scheme 17

Scheme 17: Electric Cooling Fan Wiring Diagram
Scheme 17: Electric Cooling Fan Wiring Diagram

See also:
• COOLING FAN SYSTEM