A/C mod to turn Aux Fan on right away?

[ps2cho]

This is regarding my '88 300TE.....I know you diesel guys are more experienced with the A/C systems....

My '87 260E's turns on the aux fans right away when the A/C is turned on to improve performance (must have been dealer mod) and I want to do the same with my 300TE.

Anybody know how to achieve this the easiest way?
Right now my aux fan does not turn on basically at all. I know it works because I've heard it, but the A/C never clicks it on. I think performance would be much, much better if it were running all the time when the A/C is on.

Thanks guys!