heres a good for you!!!??
 

:wonder: though it could be any one of a number of things.. my first thought is toward the ISC valve, and if it is functioning correctly.

The extra load of the fans can cause the engine revs to 'dip'. It is the function of the ISC to overcome this 'dip' and open, thus maintaning a steady idle.

Worth removing and cleaning it. Any good carburettor cleaner should work. Clean the throttle valve and MAF sensor whilst you're at it.

i have put a known good one on, but to no joy!