Every time I have pulled the plug on the two prong side of the electronic temp sensor, the thermo on the dash has been showing above 80 (about 90) but the fan still doesn't come on. Thanks to Sixto's help with the relays here...
420SEL ('87) Need Relay Legend/Diagram
I switched a few relays around to see if one was bad...and everything but the fan still works. It kicks on fine when it's hot and I blast the AC but nothing when I pull the temp sensor plug. Unless someone's got another suggestion, the next step seems to be to replace the temp sensor. I'm not running MB coolant and I'm not sure what ratio mix (coolant to H2O) my mechanic put in the system. Is it possible that the coolant mixture is just not such that it will trip the ETC?
00 A4 2.8Q