Thermofan Switch Replacement

Overview

This procedure guides you through replacing the thermofan switch on your Porsche 944 S2 with its 3.0L engine. The thermofan switch controls the cooling fans, ensuring your engine stays at the right temperature. Replacing a faulty switch prevents overheating and keeps your cooling system working efficiently.

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Tools Required

• Floor Jack
• Jack Stands
• Metric Socket Set
• 29mm (1-1/8 inch) deep socket or combination wrench
• Drain Pan

Parts Required

• Thermofan switch for Porsche 944 S2, 944 606 520 00
• New washer for thermofan switch, N 013 849 2

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Coolant System Draining, Filling, and Venting

Step-by-Step Procedure

Step 1: Disconnect the Battery

1. Locate the battery in the engine compartment and disconnect the negative terminal to ensure safety while working on the electrical system.

Step 2: Lift the Car

2. Use a floor jack to lift the front of your Porsche 944 S2.
3. Secure the car on jack stands to keep it stable while you work underneath.

Step 3: Remove the Belly Pan

3. Under the car, locate and remove the belly pan to access the radiator and cooling system components. Use your metric socket set to remove the bolts.

Step 4: Drain the Coolant

4. Place a drain pan under the radiator.
5. Find the drain plug at the bottom of the radiator on the driver’s side and remove it to drain about 2 liters (slightly more than 2 quarts) of coolant.
6. Reinstall the drain plug securely once the coolant has drained.

Step 5: Remove the Fan Assembly

5. Locate the cooling fan assembly near the radiator.
6. Remove the fan assembly to access the thermofan switch. Use your metric socket set for the bolts. (Note: Some people manage this job without removing the assembly using a long extension and socket, but removing it makes the job easier.)

Step 6: Disconnect the Thermofan Switch

6. Find the thermofan switch above and to the left of the driver’s side cooling fan.
7. Disconnect the electrical connector from the switch by gently pulling it off.

Step 7: Remove the Old Switch

7. Use a 29mm (1-1/8 inch) deep socket to loosen and remove the thermofan switch from the radiator. (Note: A 1-1/8 inch socket might work due to slight manufacturing differences, but avoid using an open-end or box-end wrench due to tight spacing.)

Step 8: Inspect the Radiator Threads

8. Check the threads in the radiator where the switch was installed to see if they are plastic or brass. This determines the torque setting for the new switch.

Step 9: Install the New Switch

9. Take the new thermofan switch (944 606 520 00) and place a new washer (N 013 849 2) on it.
10. Thread the switch into the radiator by hand to avoid cross-threading.
11. Tighten the switch with your 29mm (1-1/8 inch) deep socket. If the radiator threads are plastic, torque to 20 Nm (15 ft-lbs). If they are brass, torque to 28 Nm (21 ft-lbs).

Step 10: Reconnect the Switch

10. Reattach the electrical connector to the new thermofan switch, ensuring a firm connection.

Step 11: Reinstall the Fan Assembly

11. Place the fan assembly back into position and secure it with the bolts using your metric socket set.

Step 12: Refill and Vent the Cooling System

12. Refill the cooling system with a properly mixed coolant (refer to your Porsche 944 S2 manual for the correct mixture).
13. Follow this link to ensure this step – Coolant System Draining, Filling, and Venting – of the process is followed accurately.

Post Procedure Checklist

• Check for coolant leaks around the thermofan switch and radiator drain plug.
• Start the engine and ensure the cooling fans turn on when the engine reaches operating temperature.
• Verify the battery negative terminal is securely reconnected.
• Confirm the belly pan is properly reinstalled with no loose bolts.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• Youtube