Auto Repair Q&A



Cooling System










Auto Repair Products

My radiator fan quit working on 1993 ford escort. What could the prob be and how do I fix it?

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1. Start the engine and turn the A/C on to see if the cooling fan comes on. Perform the Key On Engine Off (KOEO) self test. During this test, the Powertrain Control Module (PCM) will command the low and high speed cooling fan to come on. If the cooling fan works during the KOEO self test, check for problems with the Engine Coolant Temperature Sensor (ECT).

2. If the cooling fan does not come on, check to see if the cooling fan fuse (40 amp) in the Battery Junction Box (BJB) is good.

3. If OK, check for power on the Black/White (BK/WH) wire at the cooling fan relay that is located in the BJB. This should be hot whenever the key is in the run position and is feed from the fuse labeled "Engine" in the BJB.

4. Check the relay ground on the Black/Red (BK/R) wire.

5. If OK, check to see if the relay "clicks" when turning the key on. If the relay does not click and the power and grounds check out OK, replace the relay.

6. If the relay does click, check for power on the Light Green/Black (LG/BK) wire. This wire should be hot when the relay is energized, and feeds power to the cooling fan high speed cooling fan relay. Replace the relay if the cooling fan fuse is good and the relay clicks when energized.

7. If the main cooling fan relay tests out OK, check for corrosion at the high speed and low speed cooling fan relays that are located next to the air filter housing.

8. At the high speed relay, the LG/BK wire connects to the Light Green (LG) with the relay not energized.
When the relay is energized, the LG/BK wire feeds power to the Light Green/Yellow (LG/Y) wire that goes to the cooling fan for high speed operation. Replace the relay if the power and grounds test out good.

SB #95-18-5 has information on a matched gauge and sender for improved accuracy. The specification is 221-224 degrees F. for low speed operation and 231-235 degrees F. for high speed operation.