Radiator Cooling Fan: Description and Operation

(Alldata Editor's Note: VW does not provide easy access to Description and Operation information for the cooling fan V7. Below is a brief explanation of the various inputs from the cooling and air conditioning systems which effect cooling fan operation. Always refer to the appropriate wiring diagrams when diagnosing cooling fan faults.)

Coolant Fan Control

The Coolant Fan (V7) is primarily controlled by the following:
- Coolant Fan Control (FC) Thermal Switch F18
- Coolant Fan Control (FC) - A/C Relay J26 (Manual A/C)
- Climatronic Control Module J255 (Climatronic)
- Coolant Fan Control (FC) Control Module J293
- A/C Pressure Switch F129 (via J293), if equipped

When A/C is off:
- F18 switches the fans on to first speed when coolant temperature is within first stage switching temperature range.
- F18 switches the fans on to second speed (via J293) when coolant temperature is within second stage switching temperature range.

When A/C is on:
- J293 switches the fans on to first speed.
- A/C Pressure Switch F129 switches the fan to the second speed (via J293) when refrigerant circuit pressure increases.

Coolant Fan Control (FC) Thermal Switch F18
Switching temperatures:
1st stage
On: 92 - 97 �C
Off: 84 - 91 �C
2nd stage
On: 99 - 105 �C
Off: 91 - 98 �C

Coolant FC (Fan Control) Control Module J293





Note: Available in different construction styles, some separate some installed on radiator fan.


This control module switches on and off the A/C clutch and therefore the A/C compressor. It switches the coolant fan and calculates the pressure in the refrigerant circuit on vehicles with High Pressure Sensor G65 or A/C Pressure/temperature Sensor G395.

A/C Pressure Switch F129






F129 has three functions:
- Switches the A/C clutch N25 off (via J293) when excessive refrigerant circuit pressure is present (e.g.: insufficient air flow over condenser or when overcharged).
- Switches the A/C clutch N25 off (via J293) when insufficient refrigerant circuit pressure is present (e.g.: when refrigerant has leaked out)
- Switches on the second speed coolant fan V7 when refrigerant circuit pressure increases.

Note:
- The presence of F129 is engine dependant. Where F129 is not used, high pressure sensor G65 is used instead.
- Always confirm system use of either F129 or G65 and applicable wiring circuit using applicable "Engine" and "Air conditioning" wiring diagrams.
- A/C Pressure Switch F129 replaces the A/C Refrigerant High Pressure Switch F23, A/C Refrigerant Low Pressure Switch F73 and the A/C Refrigerant High Pressure Switch F118.