Radiator fan switch
Radiator fan switch refers to the temperature switch used to turn on the Pontiac Fiero Radiator fan on models that use a fan switch.
The radiator fan switch is part of the cooling-system control circuit. It should not be confused with the Coolant temperature sensor used by the ECM or the Coolant temperature sender used by the dashboard Temperature gauge.
Overview
The Fiero uses several temperature-related parts, and they are often confused with one another.
The radiator fan switch is used to control the electric radiator fan.
The ECM coolant temperature sensor is used by the ECM for fuel control and diagnostics.
The coolant temperature sender is used by the instrument cluster temperature gauge and warning-light circuit.
Because these parts serve different purposes, a problem with one does not automatically mean the others are faulty.
Location
Image wanted: Photo or diagram showing the radiator fan switch location. Ideally include both the 2.8L V6 and 2.5L four-cylinder locations, and show how it differs from the ECM coolant temperature sensor and gauge sender.
The radiator fan switch is mounted on the engine.
The exact location depends on engine and year.
On the 2.8L V6, the fan switch is separate from both the ECM coolant temperature sensor and the coolant temperature gauge sender.
On the 2.5L four-cylinder, the fan-switch arrangement may vary by year and configuration.
Because temperature-related parts are close enough in purpose to be confused, identify the correct switch before replacing or testing parts.
Function
The radiator fan switch closes or changes state when coolant temperature reaches its designed threshold.
This completes the fan-control circuit and allows the radiator fan relay to turn on the radiator fan.
Related topics:
Relationship to the radiator fan
If the radiator fan motor works when powered directly or when commanded by another circuit, but does not turn on from coolant temperature, the radiator fan switch or its wiring may be part of the problem.
However, the relay, wiring, fuse, ground, fan motor, connector, and control circuit should also be checked.
Common symptoms
Possible radiator-fan-switch-related symptoms include:
- Fan does not turn on when the engine gets hot
- Engine overheats at idle or in traffic
- Fan works with air conditioning but not from temperature
- Fan turns on too late
- Fan never turns on
- Intermittent fan operation
- Temperature gauge rises while stationary
Common causes
Common causes of fan-switch-related problems include:
- Faulty fan switch
- Poor connector contact
- Broken wiring
- Corroded terminals
- Poor ground
- Failed radiator fan relay
- Failed fan motor
- Blown fuse
- Previous wiring modifications
- Incorrect switch installed
Diagnosis
Basic diagnostic checks include:
- Confirm whether the engine is actually overheating.
- Check coolant level and cooling-system condition.
- Check whether the radiator fan works when powered or commanded according to the correct test procedure.
- Check the fan fuse and relay.
- Inspect the fan switch connector.
- Inspect fan-switch wiring.
- Check for corrosion or poor contact.
- Check whether the fan operates with air conditioning if equipped.
- Test the fan switch according to the correct service procedure.
- Check the wiring diagram for the specific year and engine.
Switch versus sensor versus sender
The radiator fan switch, ECM coolant temperature sensor, and dashboard temperature sender are different parts.
The radiator fan switch controls or helps control:
The ECM coolant temperature sensor is used by:
- ECM
- Fuel mixture calculations
- Idle and warm-up behavior
- Diagnostic trouble codes such as Code 14 and Code 15
The coolant temperature sender is used by:
- Temperature gauge
- Temperature warning light, depending on year and circuit
Relationship to overheating
A bad radiator fan switch can cause overheating during idle, traffic, or low-speed driving.
However, overheating can also be caused by trapped air, low coolant, crushed coolant pipes, radiator problems, thermostat problems, water pump problems, incorrect caps, or other cooling-system faults.
Related topics:
Notes
Do not replace the ECM coolant temperature sensor when the problem is only that the radiator fan does not turn on.
Do not replace the coolant temperature gauge sender when the problem is fan control.
Correct diagnosis depends on identifying which temperature-related part is being tested.