Features and Parameters

The ISM Fan Control feature controls an OEM (Original Equipment Manufacturer) supplied fan that is often installed to meet the needs of vehicle and engine systems that rely on fan cooling for proper operation. The feature allows the fans impact on the engine to be minimized thereby promoting higher engine performance, increased fuel economy and greater durability. While many of the conditions that affect the operation of the fan are not programmable, the Fan Control feature controls fan operation in response to air conditioner refrigerant pressure, accessory demand and Engine Compression Brake engagement.

Fan Control Fan Type
If the vehicle has been installed with an engine controlled fan clutch, specify the appropriate fan type. The choices are:

  • ON/OFF - Most ECM controlled fans are classified as ON/OFF fans. many of these fans have a clutch that is air actuated. The fan is either completely engaged or disengaged.

  • HIGH/LOW/OFF - Sometimes called a 3 Speed fan.

  • Variable Speed - This type of fan has the ability to vary its speed in relation to changing cooling needs.

Fan Control Drive Ratio
Select the appropriate fan drive ratio. This is the ratio of the fan pulley rpm in relation to crankshaft pulley rpm. The range is between 0.1 and 20 (Refer to fan/vehicle manufacturer for information). Note: This parameter is not supported on engines made after October 2002.

Fan Control Maximum Fan Speed
Select the appropriate maximum fan speed. This is the maximum speed that the ECM will allow the fan to remain engaged. The range is between 0 and 4500 rpm (refer to the fan/vehicle manufacturer for information). Note: This parameter is not supported on engines made after October 2002.

Fan Control Air Conditioner Pressure Switch
Select this feature option if the vehicle is equipped with an Air Conditioner pressure switch that has been interfaced with the ECM. Enabling this parameter allows the ECM to control the fan operation in relation to air conditioner refrigerant pressure.

Fan Control Air Conditioner Timer
Specify the minimum amount of time the fan will run after activation due to Air Conditioner Pressure switch input. This parameter is required if the vehicle is equipped with an air conditioner pressure switch to control fan clutch engagement. The timer limits fan cycling and can extend the life of fan clutches and related equipment. The longer the fan runs however, the greater the impact on fuel economy. The timer should therefore be set according to customer preferences and specific operating circumstances. The range is between 0 and 3600 seconds. Note: Some vehicle OEMs use a vehicle device to control the fan AC timer. Consult your vehicle OEM dealer for details.

Fan Control Air Conditioner Vehicle Speed Control Feature
This feature incorporates vehicle speed into the operation of the fan when responding to input from the air conditioner pressure switch. By enabling this option, fan operation at high speed is minimized thereby promoting increased fuel economy and engine performance. At lower speeds, fan cycling is minimized, thereby promoting increased fan clutch and belt durability as well as reduced cab noise.

With the A/C Vehicle Speed Control feature option enabled, if the fan is operating due to A/C pressure input, it will disengage in the follow manner:

  • Below 6 mph: At vehicle speeds of less than 6 mph, once activated, the fan will continue to run until the vehicle speed exceeds 6 mph. or the engine is shut down.

  • Between 6 and 30 mph: If the vehicle is traveling between 6 and 30 mph and the fan is activated, it will disengage after it has run for at least the length of time defined by the Fan Control A/C Pressure Switch Timer parameter.

  • Above 30 mph: At vehicle speeds above 30 mph the fan will disengage as soon as the pressure switch no longer indicates a need for fan cooling. Subsequent input from the pressure switch will cause the fan to activate and deactivate as necessary.

Fan Control Fan On During Engine Braking
Select this feature option if the engine controlled fan clutch is to be engaged when the engine brake is active. The added horsepower draw associated with the fan engagement and operation helps to increase braking during engine brake use.

Manual Fan Switch
Select this feature option if the vehicle is equipped with an manual fan switch to enable the operator to manually activate or deactivate the fan. Note: A manual manual fan switch must be wired and present in the cab.

The manual fan switch is installed and enabled at the OEM. A manual fan switch must be wired and present in the cab for this feature to be enabled.

*PowerSpec currently does not support multiplexing and any multiplexed features which includes the Manual Fan Switch.*

Feature / Parameter

Range

Default

Fan Control Fan Type - Parameter

ON/OFF, HIGH/LOW/OFF, or Variable speed

ON/OFF

Fan Control Drive Ratio - Parameter

0.1 - 20

1.19

Fan Control Maximum Fan Speed - Parameter

0 - 4500 rpm

2500 rpm

Fan Control Air Conditioner Pressure Switch - Feature Option

Enable/Disable

Enable

Fan Control Air Conditioner Timer - Parameter

0 - 3600 seconds

30 seconds

Fan Control Air Conditioner Vehicle Speed Control Feature - Feature Option

Enable/Disable

Disable

Fan Control Fan On During Engine Braking - Feature Option

Enable/Disable

Enable

Manual Fan Switch - Feature Option

Enable/Disable

Disable