Cooling fan
Cooling fan |
The ICE starts and stops the cooling fan at pre-programmed coolant temperatures, see illustration, by grounding the relays.
The ICE reads the temperature for 20 minutes after the ignition has been switched off and the cooling fan can run at low speed during that time for a maximum of 3 minutes.
|
For cars with an A C system, the ICE starts the cooling fan at low speed when the pressure switch on the desiccant container closes, at about 16.5 bar. In certain hot countries there is an extra pressure switch, which closes at 22 bar. This means that the ICE starts the fan at a high speed.
If the conditions for high speed are met, the low speed will be connected for 2 seconds before high speed is switched on. In the same way the fan is switched from high speed to low speed for 2 seconds before it is switched off completely.
1. |
Fan in low-speed position
|
2. |
Fan in high-speed position (2-speed fan)
|
3. |
Car with turbocharger
|
4. |
Car without turbocharger
|
A. Ignition switch in start position (+15 on and +54 off) |
With the ignition key in start position the fan should, if it has been switched on, go from high speed to low speed and then, after 2 seconds, switch off completely.
If the fan's high-speed position is to be connected after the ignition key has been in start position, the low-speed position should be connected for 2 seconds and the fan should then switch to high-speed.
A 2-speed fan can only be run at low speed when the ignition is switched off (+15 off and +54 off). If the sensor shows readings outside the limits of -60 -- -30C (-76 -- - 22F) or +130 -- +160C (+266 -- +320F) the ICE waits for 0.5 seconds, after which the cooling fan's low speed is switched on.
B. Ignition switched off (+15 and +54 off) |
When the ignition is switched off (+15 off and +54 off), the ICE measures the coolant temperature for 20 minutes. During this time the cooling fan could be activated, but only at low speed and for a maximum of 3 minutes.
With the ignition switch in the Drive position (+15 on and +54 on) the ICE measures the coolant temperature and the pressure in the A/C system to check the cooling fan.
The ICE receives information about the coolant temperature from the temperature sensor in the cylinder block.
This information is also sent to the temperature gauge in the main instrument.