Table of contents: Two-stage electric radiator fan ↓ Radiator Thermal Switch Switching… ↓
In the Audi A4, an electric fan is installed only if there is enhanced cooling (automatic transmission, factory fitted towing device, air conditioning), it is turned on only when necessary.
Therefore, a temperature-dependent switch is built into the radiator. If it "senses" that the coolant flowing past it is still too hot after passing the radiator, it turns on the fan via a relay in socket 2 in the "eight-pin relay support". It also turns off the electric fan drive when the temperature at the bottom of the radiator drops to a certain value.
Two-stage electric radiator fan
Some versions of the Audi A4 have a two-stage electrically driven radiator fan, which, thanks to its two activation stages, can react more individually to rising coolant temperatures. This is possible thanks to a two-stage thermal switch, which activates a second current path to the fan via another relay in slot 3 in the "eight-pin relay support" and an additional resistor.
Radiator Thermal Switch Switching Temperatures
|
Fan model
|
Switch-on temperature
|
Shutdown temperature
|
| Single stage |
92–97°C
|
About 84°C
|
| Two-stage | ||
| 1st stage |
92–97°C
|
84°C
|
| 2nd stage |
99–105°C
|
91°C
|
Tip: Due to the electrical connection via terminal 30, the fan may suddenly start even when the engine is not running. Be careful when working in the engine compartment!
The thermal switch (arrow) for the electric radiator fan in vehicles with enhanced cooling is screwed to the lower left of the radiator.
[Text provided by the online resource: AudiManual.ru]