Disconnecting the auxiliary fan is definitely not fine if you plan to run the air conditioner. It needs the extra fan action when you slow down.

I don't know how the controller works on that car. On my early ('96) 210, if the fan controller fails in full-on mode (by one of the MOSFETs going to full-conductance), the fan will run all the time, even with the key removed. My fan control module (N65) is controlled directly by N22, so if I had this problem, I'd suspect N22 rather than N65. Later 210's use a completely different set of parts, including the (rather expensive) N10-1 in the fan control path. But of course, few if any of the prior part designations apply to your car.

Please note: I'm not one of these "single guys" crawling over this posting, but rather quite happily attached.