Cooling System
Thermofan Switch Replacement
This guide is preserved from Clark's Garage, a foundational 944 resource. View the original →
Tools you'll need
- Various Coolant Pressure Tester
- Fluke 117 / Klein MM400 Digital Multimeter (4000+ count)
- Various Torque Wrench — 10–130 Nm
See the full tools list for where to buy each one and budget alternatives.
Torque specifications
Quick reference for the fasteners in this procedure — see the steps below for full context, and verify against your model year.
| Fastener | Size | Torque |
|---|---|---|
| Thermofan switch — plastic radiator threads | — | 20 Nm (≈15 ft-lb) |
| Thermofan switch — brass radiator threads | — | 28 Nm (≈21 ft-lb) |
Tools Needed
- Floor Jack.
- Jack Stands
- Metric Socket Set
- 29mm or 1-1/8” deep socket or combination wrench
- Drain pan
Other Procedures Needed
- COOL-02, Cooling System Draining, Filling, and Venting
Procedure
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Disconnect negative terminal of the battery.
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Jack car and place the front end on jack-stands.
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Remove the belly pan.
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Drain approximately 2 liters (slightly more than 2 qts.) of coolant system from the radiator by removing the drain plug at the bottom of the radiator on the driver’s side. Reinstall the plug after the required amount of coolant has been drained.
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Remove the fan assembly. I’ve talked to a few people who have done this job without removing the fan assembly using a long handle extension and a socket. However, I’ve never had much luck using that method.
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Above and to the left of the driver’s side cooling fan is the switch.
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Disconnect the electrical connector from the switch.
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Using a 29mm deep socket, remove the switch.
NOTE
Due to differences in manufacturing tolerances, you may find a 1-1/8” deep socket that will fit. However, due to the tight space, it’s almost impossible to remove the switch with an open end or box end wrench.
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Check the threads in the radiator to determine if they are plastic or brass.
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Replace the switch with the new one, making sure you use a new washer.
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If the threads in the radiator for the switch are plastic, torque the switch to 20 Nm. If the threads are brass torque the switch to 28 Nm.
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Reconnect the electrical connector to the switch.
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Reinstall the fan assembly.
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Fill coolant system with properly mixed coolant and vent using the COOL-02 procedure.