ISC Fan Clutch Replacement $4000+ ?

elhajj33 wrote:

usersmanual wrote:

11178adm wrote:
if the fan never turns off you may have a problem with the a/c high pressure curcuit, it could be a switch or wiring issue

no

Actually there's some truth to that statement.

This from cummins (linklink):

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.

This would possible be the case when the AC condenser was attached to the rad and the engine cooling fan also cooled the AC system
most DP I have owned and seen have a stand alone electric fan that cools the dash AC system condenser
therefore that's why I said no