Change the switch...its most likely the fan switch. Inexpensive. Give your vin# and you should get the right one but I believe there is only one 3 prong one. The secondary fan will kick in when the AC is on. Does the override switch engage the big fan? I have never seen this...is it an aftermkt add on? If so is it fused?
88 230E (W124)
98 e420 sport replicas