Thermofan Switch Replacement – 2.5L NA

Overview

This procedure outlines the steps to replace the thermofan switch on all Porsche 944 variants (8-valve engine) for pre-1985.5 (83-85.5) and 1985.5 onwards (86-88) models. The thermofan switch controls the radiator cooling fan, ensuring proper engine temperature regulation. Replacing a faulty switch prevents overheating and maintains optimal performance.

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Tools Required

• Floor jack
• Jack stands
• Metric socket set
• 29mm (1-1/8 inch) deep socket or combination wrench
• 10mm (3/8 inch) wrench
• Drain pan

Parts Required

• Thermofan switch, 944 606 141 00
• Washer, 900 123 118 30

Required Additional Procedures

Steps in these procedures are required to complete this process:

• Cooling System Draining, Filling, and Venting

Step-by-Step Procedure

Step 1: Prepare the Vehicle

1. Disconnect the negative terminal of the battery using a 10mm (3/8 inch) wrench to ensure electrical safety.
2. Raise the front of the car using a floor jack and secure it on jack stands.
3. Remove the belly pan under the engine bay using a metric socket set to access the radiator and fan assembly.

Step 2: Drain the Coolant

4. Place a drain pan under the radiator.
5. Locate the drain plug at the bottom of the radiator on the driver’s side.
6. Remove the drain plug using a metric socket or wrench to drain approximately 2 liters (2.1 quarts) of coolant. This is about 0.5 gallons (1.9 km of liquid volume).
7. Reinstall the drain plug securely after draining.

Step 3: Remove the Fan Assembly

8. Remove the driver’s side cooling fan assembly using a metric socket set to access the thermofan switch. Note: Some mechanics may attempt this without removing the fan using a long extension and socket, but removing the assembly is recommended for better access.

Step 4: Replace the Thermofan Switch

9. Locate the thermofan switch above and to the left of the driver’s side cooling fan.
10. Disconnect the electrical connector from the switch by gently pulling it off.
11. Using a 29mm (1-1/8 inch) deep socket, remove the thermofan switch. Note: A 1-1/8 inch socket may fit due to manufacturing tolerances, but avoid using an open-end or box-end wrench due to limited space.
12. Inspect the new thermofan switch, 944 606 141 00, for defects such as damaged threads or cracks.
13. Check the radiator threads where the switch installs to determine if they are plastic (Pre-85.5) or brass (85.5 Onwards).

For Pre-85.5 models:
Install the new thermofan switch with a new washer, 900 123 118 30, and torque to 20 Nm (15 ft-lbs).

For 85.5 Onwards models:
Install the new thermofan switch with a new washer, 900 123 118 30, and torque to 28 Nm (21 ft-lbs).

14. Reconnect the electrical connector to the new switch, ensuring a secure fit.

Step 5: Reassemble and Refill

15. Reinstall the fan assembly using a metric socket set, ensuring all bolts are tightened securely.
16. Fill and vent the cooling system with a properly mixed coolant solution. Follow this link to ensure this step – Cooling System Draining, Filling, and Venting – of the process is followed accurately.

Post Procedure Checklist

• Check the coolant level and top off if necessary.
• Inspect for coolant leaks around the thermofan switch and drain plug.
• Confirm the cooling fan activates when the engine reaches operating temperature.
• Ensure the battery negative terminal is securely reconnected.
• Verify no tools or debris are left in the engine bay.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manuals
• YouTube