Radiator fan switch: Difference between revisions
Created page with "'''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 c..." |
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'''Radiator fan switch''' refers to the temperature switch used to | '''Radiator fan switch''' refers to the coolant-temperature switch used to control the [[Pontiac Fiero]] [[Radiator fan]] on systems that use a separate fan switch. | ||
The radiator fan switch is part of the cooling- | The radiator fan switch is part of the cooling-fan 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 == | == Overview == | ||
| Line 7: | Line 7: | ||
The Fiero uses several temperature-related parts, and they are often confused with one another. | The Fiero uses several temperature-related parts, and they are often confused with one another. | ||
The radiator fan switch | The radiator fan switch, where used, controls or helps control the electric radiator fan. | ||
The ECM coolant temperature sensor is used by the ECM for fuel control and diagnostics. | The ECM coolant temperature sensor is used by the ECM for fuel control, warm-up behavior, and diagnostics. | ||
The coolant temperature sender is used by the instrument cluster temperature gauge | The coolant temperature sender or temperature switch is used by the instrument cluster temperature gauge or warning-light circuit, depending on year and equipment. | ||
Because these parts serve different purposes, a problem with one does not automatically mean the others are faulty. | Because these parts serve different purposes, a problem with one does not automatically mean the others are faulty. | ||
Related topics: | |||
* [[Radiator fan]] | |||
* [[Radiator fan relay]] | |||
* [[Coolant temperature sensor]] | |||
* [[Coolant temperature sender]] | |||
* [[Temperature gauge]] | |||
== Location == | == Location == | ||
| Line 19: | Line 27: | ||
{{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.}} | {{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 radiator fan switch is mounted on the engine cooling system. | ||
The exact location depends on engine and | The exact location depends on engine, year, and equipment. | ||
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 2.8L V6, the fan switch is separate from both the ECM coolant temperature sensor and the coolant temperature gauge sender. | ||
| Line 31: | Line 39: | ||
== Function == | == Function == | ||
The radiator fan switch | The radiator fan switch changes state when coolant temperature reaches its designed threshold. | ||
In a switch-controlled system, the fan switch controls the relay side of the radiator fan circuit. The relay then switches power to the radiator fan motor. | |||
Factory service information describes the coolant temperature fan switch as regulating voltage to the coolant fan relay, which operates the fan when engine coolant temperature exceeds approximately 230°F / 110°C. | |||
A fan that does not turn on until a high indicated temperature does not automatically mean the fan switch has failed. The fan-on temperature is relatively high compared with normal thermostat opening temperature. | |||
Related topics: | Related topics: | ||
| Line 41: | Line 53: | ||
* [[Cooling system]] | * [[Cooling system]] | ||
* [[Electrical system]] | * [[Electrical system]] | ||
== Fan switch versus relay == | |||
The radiator fan switch is the temperature-related control device. | |||
The radiator fan relay is the electrical power-switching device. | |||
The switch or control circuit activates the relay. | |||
The relay powers the fan motor. | |||
The fan motor current should not normally be routed directly through the temperature switch. | |||
Related topic: | |||
* [[Radiator fan relay]] | |||
== Switch-controlled and ECM-controlled systems == | |||
Fiero fan-control strategy depends on model year, engine, and equipment. | |||
Some systems use a coolant temperature fan switch to operate the radiator fan relay. | |||
ECM-controlled systems use the ECM to provide the relay control path. In those systems, the ECM may command fan operation based on coolant temperature, A/C request, or certain coolant-temperature-sensor faults. | |||
Because both types of control may be discussed in Fiero troubleshooting, identify the actual system before testing or replacing parts. | |||
Related topics: | |||
* [[ECM]] | |||
* [[Coolant temperature sensor]] | |||
* [[Code 14]] | |||
* [[Code 15]] | |||
== Air-conditioning relationship == | |||
On air-conditioned cars, the radiator fan may run when the air conditioning is selected. | |||
This means the fan may still work through the A/C-related control path even if the temperature-switch path has a problem. | |||
Factory A/C diagnostic information includes checking engine cooling fan operation with the ignition on, engine off, A/C selected, and the engine coolant temperature fan switch disconnected. In that test, the cooling fan should run. | |||
If the fan works with air conditioning but not from coolant temperature, the fan motor and part of the relay/wiring circuit may be functional, while the temperature-switch or temperature-control side still needs diagnosis. | |||
If the fan does not work with either air conditioning or high coolant temperature, check the fan motor, relay, power feed, ground, wiring, and control circuit. | |||
Related topic: | |||
* [[Air conditioning]] | |||
== Relationship to the radiator fan == | == Relationship to the radiator fan == | ||
| Line 46: | Line 107: | ||
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. | 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. | However, the relay, wiring, fuse or fusible link, ground, fan motor, connector, and control circuit should also be checked. | ||
Related topics: | |||
* [[Radiator fan]] | |||
* [[Radiator fan relay]] | |||
* [[Ground problems]] | |||
* [[Wiring diagrams]] | |||
== 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: | |||
* [[Radiator fan]] | |||
* [[Radiator fan relay]] | |||
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]] | |||
* ECM-controlled fan operation, where applicable | |||
The coolant temperature sender or temperature switch is used by: | |||
* [[Temperature gauge]] | |||
* Temperature warning light, depending on year and circuit | |||
A fan problem should not automatically be diagnosed as an ECM coolant temperature sensor problem, and a gauge problem should not automatically be diagnosed as a radiator fan switch problem. | |||
== Common symptoms == | == Common symptoms == | ||
| Line 54: | Line 146: | ||
* Fan does not turn on when the engine gets hot | * Fan does not turn on when the engine gets hot | ||
* Engine overheats at idle or in traffic | * Engine overheats at idle or in traffic | ||
* Fan works with air conditioning but not from temperature | * Temperature drops when driving faster | ||
* Fan works with air conditioning but not from coolant temperature | |||
* Fan turns on too late | * Fan turns on too late | ||
* Fan never turns on | * Fan never turns on | ||
* Intermittent fan operation | * Intermittent fan operation | ||
* Temperature gauge rises while stationary | * Temperature gauge rises while stationary | ||
* Fan switch connector is loose, corroded, or damaged | |||
* Incorrect temperature-related part was replaced | |||
== Common causes == | == Common causes == | ||
| Line 65: | Line 160: | ||
* Faulty fan switch | * Faulty fan switch | ||
* Poor connector contact | * Poor fan-switch connector contact | ||
* Broken wiring | * Broken fan-switch wiring | ||
* Corroded terminals | * Corroded terminals | ||
* Poor ground | * Poor ground or control-circuit path | ||
* Failed radiator fan relay | * Failed radiator fan relay | ||
* Failed fan motor | * Failed fan motor | ||
* Blown fuse | * Blown fuse or fusible-link problem | ||
* Previous wiring modifications | * Previous wiring modifications | ||
* Incorrect switch installed | * Incorrect switch installed | ||
* Confusion with the ECM coolant temperature sensor | |||
* Confusion with the temperature gauge sender or warning-light switch | |||
== Diagnosis == | == Diagnosis == | ||
| Line 81: | Line 178: | ||
# Confirm whether the engine is actually overheating. | # Confirm whether the engine is actually overheating. | ||
# Check coolant level and cooling-system condition. | # Check coolant level and cooling-system condition. | ||
# Confirm which temperature-related component is the radiator fan switch. | |||
# Check whether the radiator fan works when powered or commanded according to the correct test procedure. | # Check whether the radiator fan works when powered or commanded according to the correct test procedure. | ||
# Check the fan fuse | # Check the fan fuse, fusible-link feed, or related power supply. | ||
# Check the radiator fan relay. | |||
# Inspect the fan switch connector. | # Inspect the fan switch connector. | ||
# Inspect fan-switch wiring. | # Inspect fan-switch wiring. | ||
# Check for corrosion or poor contact. | # Check for corrosion, damaged terminals, or poor contact. | ||
# Check whether the fan operates with air conditioning if equipped. | # Check whether the fan operates with air conditioning if equipped. | ||
# Test the fan switch according to the correct service procedure. | # Test the fan switch according to the correct service procedure. | ||
# Check the wiring diagram for the specific year and | # Check the wiring diagram for the specific year, engine, and equipment. | ||
Do not replace the ECM coolant temperature sensor or temperature gauge sender until the correct part has been identified. | |||
== Testing cautions == | |||
The | The fan switch is part of an electrical control circuit, but the cooling system can be hot and pressurized when fan operation is being checked. | ||
When testing the fan-switch circuit: | |||
* Keep hands, tools, wiring, and clothing away from the fan. | |||
* Remember that the fan may start unexpectedly. | |||
* Do not open the cooling system when hot or pressurized. | |||
* Use the correct wiring diagram. | |||
* Identify whether the car uses switch-controlled or ECM-controlled fan logic. | |||
* Do not bypass fuse or fusible-link protection. | |||
* Avoid probing connectors in a way that damages terminals. | |||
== Relationship to overheating == | |||
A bad radiator fan switch can cause overheating during idle, traffic, or low-speed driving. | |||
If the car cools normally at road speed but overheats while stationary, the radiator fan system should be checked. | |||
However, overheating can also be caused by: | |||
* Trapped air | |||
* Low coolant | |||
* Crushed coolant pipes | |||
* Restricted radiator | |||
* Incorrect or faulty radiator cap | |||
* Incorrect or faulty thermostat | |||
* Water pump problem | |||
* Collapsed hose | |||
* Poor coolant flow | |||
* Incorrect coolant filling procedure | |||
* Temperature gauge or sender problem | |||
Related topics: | Related topics: | ||
| Line 124: | Line 233: | ||
* [[Water pump]] | * [[Water pump]] | ||
* [[Coolant pipes]] | * [[Coolant pipes]] | ||
== Manual fan switches == | |||
Some owners add a manual fan switch to turn the radiator fan on from inside the car. | |||
A manual fan switch is usually wired into the relay control side of the circuit rather than carrying fan-motor current directly. | |||
A manual switch may be useful as a diagnostic aid or temporary backup, but it should not be used to hide an unresolved cooling-system, relay, fan-motor, or fan-switch problem. | |||
For a stock car, the original fan-control circuit should normally be diagnosed and repaired rather than bypassed. | |||
== Notes == | == Notes == | ||
| Line 132: | Line 251: | ||
Correct diagnosis depends on identifying which temperature-related part is being tested. | Correct diagnosis depends on identifying which temperature-related part is being tested. | ||
The fan switch controls the fan circuit only on systems that use a separate fan switch. ECM-controlled fan systems should be diagnosed according to the correct ECM and wiring information. | |||
== See also == | == See also == | ||
| Line 142: | Line 263: | ||
* [[Coolant temperature sender]] | * [[Coolant temperature sender]] | ||
* [[Temperature gauge]] | * [[Temperature gauge]] | ||
* [[ECM]] | |||
* [[Code 14]] | |||
* [[Code 15]] | |||
* [[Air conditioning]] | |||
* [[Electrical system]] | * [[Electrical system]] | ||
* [[Wiring diagrams]] | * [[Wiring diagrams]] | ||
Latest revision as of 00:22, 19 July 2026
Radiator fan switch refers to the coolant-temperature switch used to control the Pontiac Fiero Radiator fan on systems that use a separate fan switch.
The radiator fan switch is part of the cooling-fan 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, where used, controls or helps control the electric radiator fan.
The ECM coolant temperature sensor is used by the ECM for fuel control, warm-up behavior, and diagnostics.
The coolant temperature sender or temperature switch is used by the instrument cluster temperature gauge or warning-light circuit, depending on year and equipment.
Because these parts serve different purposes, a problem with one does not automatically mean the others are faulty.
Related topics:
- Radiator fan
- Radiator fan relay
- Coolant temperature sensor
- Coolant temperature sender
- Temperature gauge
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 cooling system.
The exact location depends on engine, year, and equipment.
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 changes state when coolant temperature reaches its designed threshold.
In a switch-controlled system, the fan switch controls the relay side of the radiator fan circuit. The relay then switches power to the radiator fan motor.
Factory service information describes the coolant temperature fan switch as regulating voltage to the coolant fan relay, which operates the fan when engine coolant temperature exceeds approximately 230°F / 110°C.
A fan that does not turn on until a high indicated temperature does not automatically mean the fan switch has failed. The fan-on temperature is relatively high compared with normal thermostat opening temperature.
Related topics:
Fan switch versus relay
The radiator fan switch is the temperature-related control device.
The radiator fan relay is the electrical power-switching device.
The switch or control circuit activates the relay.
The relay powers the fan motor.
The fan motor current should not normally be routed directly through the temperature switch.
Related topic:
Switch-controlled and ECM-controlled systems
Fiero fan-control strategy depends on model year, engine, and equipment.
Some systems use a coolant temperature fan switch to operate the radiator fan relay.
ECM-controlled systems use the ECM to provide the relay control path. In those systems, the ECM may command fan operation based on coolant temperature, A/C request, or certain coolant-temperature-sensor faults.
Because both types of control may be discussed in Fiero troubleshooting, identify the actual system before testing or replacing parts.
Related topics:
Air-conditioning relationship
On air-conditioned cars, the radiator fan may run when the air conditioning is selected.
This means the fan may still work through the A/C-related control path even if the temperature-switch path has a problem.
Factory A/C diagnostic information includes checking engine cooling fan operation with the ignition on, engine off, A/C selected, and the engine coolant temperature fan switch disconnected. In that test, the cooling fan should run.
If the fan works with air conditioning but not from coolant temperature, the fan motor and part of the relay/wiring circuit may be functional, while the temperature-switch or temperature-control side still needs diagnosis.
If the fan does not work with either air conditioning or high coolant temperature, check the fan motor, relay, power feed, ground, wiring, and control circuit.
Related topic:
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 or fusible link, ground, fan motor, connector, and control circuit should also be checked.
Related topics:
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
- ECM-controlled fan operation, where applicable
The coolant temperature sender or temperature switch is used by:
- Temperature gauge
- Temperature warning light, depending on year and circuit
A fan problem should not automatically be diagnosed as an ECM coolant temperature sensor problem, and a gauge problem should not automatically be diagnosed as a radiator fan switch problem.
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
- Temperature drops when driving faster
- Fan works with air conditioning but not from coolant temperature
- Fan turns on too late
- Fan never turns on
- Intermittent fan operation
- Temperature gauge rises while stationary
- Fan switch connector is loose, corroded, or damaged
- Incorrect temperature-related part was replaced
Common causes
Common causes of fan-switch-related problems include:
- Faulty fan switch
- Poor fan-switch connector contact
- Broken fan-switch wiring
- Corroded terminals
- Poor ground or control-circuit path
- Failed radiator fan relay
- Failed fan motor
- Blown fuse or fusible-link problem
- Previous wiring modifications
- Incorrect switch installed
- Confusion with the ECM coolant temperature sensor
- Confusion with the temperature gauge sender or warning-light switch
Diagnosis
Basic diagnostic checks include:
- Confirm whether the engine is actually overheating.
- Check coolant level and cooling-system condition.
- Confirm which temperature-related component is the radiator fan switch.
- Check whether the radiator fan works when powered or commanded according to the correct test procedure.
- Check the fan fuse, fusible-link feed, or related power supply.
- Check the radiator fan relay.
- Inspect the fan switch connector.
- Inspect fan-switch wiring.
- Check for corrosion, damaged terminals, 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, engine, and equipment.
Do not replace the ECM coolant temperature sensor or temperature gauge sender until the correct part has been identified.
Testing cautions
The fan switch is part of an electrical control circuit, but the cooling system can be hot and pressurized when fan operation is being checked.
When testing the fan-switch circuit:
- Keep hands, tools, wiring, and clothing away from the fan.
- Remember that the fan may start unexpectedly.
- Do not open the cooling system when hot or pressurized.
- Use the correct wiring diagram.
- Identify whether the car uses switch-controlled or ECM-controlled fan logic.
- Do not bypass fuse or fusible-link protection.
- Avoid probing connectors in a way that damages terminals.
Relationship to overheating
A bad radiator fan switch can cause overheating during idle, traffic, or low-speed driving.
If the car cools normally at road speed but overheats while stationary, the radiator fan system should be checked.
However, overheating can also be caused by:
- Trapped air
- Low coolant
- Crushed coolant pipes
- Restricted radiator
- Incorrect or faulty radiator cap
- Incorrect or faulty thermostat
- Water pump problem
- Collapsed hose
- Poor coolant flow
- Incorrect coolant filling procedure
- Temperature gauge or sender problem
Related topics:
Manual fan switches
Some owners add a manual fan switch to turn the radiator fan on from inside the car.
A manual fan switch is usually wired into the relay control side of the circuit rather than carrying fan-motor current directly.
A manual switch may be useful as a diagnostic aid or temporary backup, but it should not be used to hide an unresolved cooling-system, relay, fan-motor, or fan-switch problem.
For a stock car, the original fan-control circuit should normally be diagnosed and repaired rather than bypassed.
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.
The fan switch controls the fan circuit only on systems that use a separate fan switch. ECM-controlled fan systems should be diagnosed according to the correct ECM and wiring information.