Scheme of switching on the electric motor of the fan of the engine cooling system
1 - sensor for turning on the electric motor; 2 - fan motor; 3 - the relay of inclusion of the electric motor; 4 - main fuse box; 5 - ignition switch; 6 - additional fuse block; 7 - generator; 8 - battery.
On some vehicles, an electric fan is provided for blowing the radiator of the cooling system with air. It turns on when the sensor-switch 37101B, installed at the bottom of the right radiator tank, is triggered. Previously, the fan motor was powered by a relay. In this case, a TM-108 temperature sensor was used. At present, the electric fan circuit is simplified and the electric motor is powered directly through the contacts of the sensor-switch. The sensor is non-separable - in case of a malfunction, it must be replaced.
Electric motor ME-272 (or similar) - direct current with excitation from permanent magnets. It is installed in a casing fixed on the radiator brackets. During operation, the electric motor does not require maintenance, the faulty one must be replaced.
Technical data of electric fan and sensor 37101B (TM-108)
Rated frequency of rotation of the motor shaft with impeller, min–1 | 2500 – 2800 |
Consumed current of the electric motor, A | 14 |
Sensor contact closing temperature,°C | 82±2 (82 ±2) |
Sensor contact opening temperature,°C | 87±2 (87±2) |
The engine overheats, the electric fan does not turn on.
To check the fan motor, we apply 12 V voltage from the battery to the motor terminals - a serviceable motor will start.
To check the temperature sensor of the electric fan, disconnect the wires from the temperature sensor, connect them together with the ignition on. If the fan works, the sensor is faulty.
By connecting an ohmmeter to the sensor terminals and lowering it to the length of the thread in water, we measure the temperature on and off the sensor with a thermometer. To do this, heat the water almost to a boil, and then control the cooling. For a serviceable sensor, the temperature characteristic should not differ from that given above.