90 RS Fan Problems

My engine cooling fan seems to have a mind of it’s own. I have had the car for about a month, and after a new thermostat, nothing has changed. The cooling fan will just turn off and on as it pleases, even when the weather is very cold. It will cool down the car for 15 minutes- shut off- then 10 minutes later, turn back on again. The car is running fine, and the temperature of the car is perfect with the new thermostat. There was even one point where the fan stayed on for an hour straight, and even for more than two hours straight. What seems to be the culprit here? The coolant temperature sensor? The little skinny sensor beside it…temperature sensor of some kind? Or could it be the fan relay block beside the fan, or a fan timer relay of some sort? I don’t know where to start looking. If anybody has had a similar problem like this in the past, with fans that stay on way too long, let me know what your solution was. Thanks.

how do you know the temp is ok? you seem to know the components. are you burning up fluid? radiator cap? you might just want to check the haynes manual troubleshooter

yeah mine does the same thing. sometimes just turning the key on without starting will cause it it to kick on even if it sits overnight. someone posted about it a while ago & i think it was mentioned that there is a sensor that goes bad on high milage cars especially, but the sensor was like $130 at the dealer so I am just dealing with it for now. if anybody knows please do a teg tip on this

Yeah, if anybody has had any problems with this non-stop fan problem, we should get a teg tip devoted to it. My RS runs fine on short trips- no fan problems at all. What drives me crazy is when I make the long trips, like 30 minutes plus. The fan will kick on for 20 mins., stop, and then turn on again. Or it may run for 2 hours straight. It has a mind of it’s own. No check engine and no codes. I have the Haynes manual, and I was just wondering out there if anybody solved the problem in the past. If not, I guess I have to start changing sh*t one by one. Today was a start at least. The dude who replaced the original engine in my car at 170,000, who dropped in a used one with only 70,000 on it, let me pull all the remaining sensors of the orig today. Later.

look at my post in teg tips about condenser fans that will not turn off. Hope that helps