DESCRIPTION
The flex-blade fan assembly is designed to allow blades to flex as engine RPM increases. Blade pitch decreases as RPM increases, thereby saving power and decreasing noise level. Keep fan belt adjusted to proper tension as necessary. (Scheme 1)
Many air conditioned models use a thermostatically controlled fluid fan and torque control clutch. Thermal control drive is a silicone-filled coupling connecting fan to a fan pulley, and is operated by an internal control valve. The control valve is operated by a temperature sensitive bi-metallic coil (or strip) and controls flow of silicone through the clutch. (Scheme 2)
During periods of operation when radiator discharge air temperature is low, fan clutch speeds are slowed, decreasing fan speed and increasing engine warm-up. High radiator discharge air temperature causes bi-metallic coil or strip to allow a greater flow of silicone to enter clutch. This increases drag between driven member and driving member resulting in a higher fan speed and increased cooling.
Typical Flex Blade Fan. Scheme 1
Typical Thermostatically Controlled Fan Assembly. Scheme 2
THERMOSTATICALLY CONTROLLED FAN ASSEMBLY TEST
- In cases of engine overheating or insufficient air conditioning, start with a cool engine to ensure complete fan clutch disengagement. Cover radiator grille to induce high engine temperature.
- Start engine and operate at 2000 RPM. Turn on air conditioning (if equipped). When radiator discharge air temperature gets hot, a fan roar will be noticed when fan clutch engages. NOTE: It takes approximately 5-10 minutes for temperature to become hot enough to allow engagement of fan clutch. While operating engine under this condition, observe temperature light or gauge to prevent overheating. If car overheats, remove cover from radiator grille.
- When clutch engages, remove radiator grille cover and turn A/C off to assist in engine cooling. After several minutes fan clutch should disengage. This can be determined by a reduction in fan speed and roar. If fan clutch fails to function as described, it should be replaced.
TESTING/DIAGNOIS (ALL EXCEPT 5.0L VIN E)
Note. See appropriate C12 CHART in the ENGINE PERFORMANCE section
SYSTEM DIAGNOSIS
Determine system failure. See SYSTEM DIAGNOSIS table. Perform proper test procedure.
| Symptom | Diagnosis |
|---|---|
| Cooling Fan Inoperative With High Engine Temperature & A/C On | Do TEST A |
| Cooling Fan Inoperative With High Engine Temperature, But Runs With A/C On | Do TEST B |
| Cooling Fan Inoperative With A/C On, But Runs With High Engine Temperature | Do TEST C |
| Cooling Fan Will Not Turn Off | Do TEST D |
| Cooling Fan Runs With Ignition Switch Off | Replace Cooling Fan Relay |
SYSTEM DIAGNOSIS
TEST A - COOLING FAN OPEN TEST 1
With cooling fan relay connected install fused jumper wire between between F (Dark Green/White) wire and ground. If cooling fan runs, check for an open in Dark Green/White wire. If cooling fan does not run, see TEST A - COOLING FAN OPEN TEST 2 .
TEST A - COOLING FAN OPEN TEST 2
- Disconnect cooling fan relay.
- Connect a test lamp between D (Brown) wire and ground. If lamp lights, proceed to «TEST A - COOLING FAN OPEN TEST NO. 3»(/cadillac/brougham/i-1987-1992/remont/cooling-fan/#engine-cooling-fan-rwd__test-a-cooling-fan-open) . If lamp does not light check FP-FAN Fuse and Brown wire for opens.
- Connect a test lamp between E (Red) wire and ground. If lamp lights, proceed to «TEST A - COOLING FAN OPEN TEST NO. 3»(/cadillac/brougham/i-1987-1992/remont/cooling-fan/#engine-cooling-fan-rwd__test-a-cooling-fan-open) . If lamp does not light, check Fusible Link E and Red wire for opens.
TEST A - COOLING FAN OPEN TEST 3
- Disconnect cooling fan relay.
- Install fused jumper wire between E Red and A Black/Red wires of connector. If cooling fan runs, replace cooling fan relay. If cooling fan does not run, leave fused jumper in place and proceed to «TEST A - COOLING FAN OPEN TEST 4»(/cadillac/brougham/i-1987-1992/remont/cooling-fan/#engine-cooling-fan-rwd__test-a-cooling-fan-open) .
TEST A - COOLING FAN OPEN TEST 4
- Ensure cooling fan relay is disconnected and fused jumper is in place from «TEST A - COOLING FAN OPEN TEST 3»(/cadillac/brougham/i-1987-1992/remont/cooling-fan/#engine-cooling-fan-rwd__test-a-cooling-fan-open) .
- Connect a test lamp between B (Black/Red) wire and ground. If lamp lights, replace cooling fan. If lamp does not light, check Black/Red wire for an open.
- Connect a test lamp between B (Black/Red) wire and A (Black) wire. If lamp lights, replace cooling fan. If lamp does not light, check Black wire for an open.
TEST B - COOLING FAN SWITCH TEST
- Disconnect cooling fan switch connector.
- Install fused jumper wire between Black wire and ground. If cooling fan runs, replace cooling fan switch. If cooling fan does not run, check Black wire for an open.
TEST C - A/C CONTROL HEAD TEST
- Disconnect A/C control head connector.
- Install fused jumper wire between B (Dark Green) wire and ground. If cooling fan runs, replace A/C control head. If cooling fan does not run, check Dark Green and Dark Green/White wires for an open.
- Install fused jumper wire between B (Dark Green) and A (Black) wire. If cooling fan runs, replace A/C control head. If cooling fan does not run, check Black wire for an open.
TEST D - COOLING FAN SHORT TEST
- With ignition switch in RUN, remove cooling fan switch. If fan continues to run, go to step 2. If fan turns off, replace cooling fan switch.
- Remove FP-FAN fuse. If fan continues to run, replace cooling fan relay. If fan turns off, check A/C control Head, and Dark Green wire for a short to ground.
Cooling Fan Wiring Diagram (5.0L VIN E). Scheme 3
See also:
• SYSTEM DIAGNOSIS
• TEST A
• TEST B
• TEST C
• TEST D