Yes the SL's and SLC's have identical systems. You are inquiring about the 212 F. switch on the thermostat housing. I have a 80 SLC and experiencing the same issue. I will take MBTECH's advice and ground out the switch to the housing to see if switch is good. I believe when the vehicle temp. reaches 212F the switch closes and the fan activates. Grounding the switch will simulate that effect.