Created: 10. 11. 2003
— Introduction —This page explains the basic principle of the various operating modes of the Peugeot 306 cooling fans.
The example we are using here is the two speed twin fans controled by a cooling fan ECU. Vehicle manufactured 1996 with A/C and 30 fuse box.
This system is used in most Australian models with petrol engines. Although the basic circuit remains the same in later models the fuse and wire numbers will be different.
— Overview of the system —The engine cooling fan system is made up of the folowing parts. 2 fan motors, 3 relays, control unit and the coolant temperature thermistor (NTC).
The fans have 2 functions.
1. To provide engine cooling in slow or stationary traffic conditions.
2. To provide constant airflow for the condenser when the A/C is operating.
The 2 fan motors always run together and have 2 speeds available. At low speed the motors' power circuit is switched in series and at high speed the circuit is changed over to parallel. A ballast resistor is therefore not required. The switching of the power circuit is done by the 3 relays which, are controlled by the control unit.
The following tasks can be performed by the control unit: Switching of the fan relays, illuminating the "STOP" warning light, illuminate the warning light on the temperature gauge, prevent the A/C compressor from operating under extreme engine temperature or under full engine load, timed post cooling when engine is shut down with the fans operating.
In order to carry out these tasks it receives inputs from the coolant temperature sensor, the air conditioning control panel, the refrigerant pressostat and the engine ECU.
— Fan and relay layout —
Use this graphic to identify and relate the components to the diagrams.
— Location Of Components —Control Unit
The cooling fan control unit is located under the left guard below the head light. Remove the inner guard cover to gain access.
The temperature sensor us mounted on the heather tank on the cylinder head at the bell housing end. The sensor is brown with a brown 2 way connector.
Fuse 33 and 34 in the fuse box near the battery.
Fuses (relay coils)
Fuse box with 30 fuses in passengers compartment.
Fuse 7, battery + to left fan relay and control unit.
Fuse 3, ignition + to right fan relay and change over relay.
Fuse 2, ignition + to control unit.
Earth connection 1
On the left chassis rail in front and below the battery carrier.
A/C Control Unit
Integrated in the control panel on the dash board.
— System at rest diagram —
— Low Speed Operation —
Condition for low speed call
The low fan speed is called for:
Power circuit explained
Only the "left fan relay" is energised. This relay has a permanent battery + supply
from fuse 7 (fuse 10 for a 13 fusebox) in the passenger compartment fusebox.
— High Speed Operation —
Condition for high speed call
The high fan speed is called for:
Power circuit explained
All 3 relays are now energised.
Technical information by