Yep, probably you are right. A Mickey Mouse “madness mechanic” was previous owner. Any suggestions? I ask, because you gave most “relevant” answer. A red wire (not the positive for batter) is coming out of the lower area of engine (not sure where yet). When connected to positive car starts but fans keep running. when disconnected car wont start and no fans are running. Any clues you might have could be helpful. Thanks.
OH. And this happens when the car is dead cold.
Yeah, sounds like hacked wiring to get the car running. You’ll have to decide if it’s worth it to rewire correctly.
What do you mean by “it won’t start”. Does it not crank — than rrr rr rr sound. Or does it crank ok, but won’t catch and run? You don’t mean that when that wire is connected the engine cranks on its own without turning the key to “start”, right?
hmmm … then the other mystery, connecting that red wire to battery + causes the fan to run all the time. Well, that is indeed a mystery. Some Sherlock Holmes type of investigation is going to be necessary to figure that one out. Someone’s going to have to physically trace where that wire goes to in the wiring harness, then with the aid of a wiring diagram I expect all can finally be deciphered.
Yup, and the fan too if there’s no delay system to keep it running. Underhood temperatures rise when you shut the engine down as the engine’s internal temperatures radiate out its sides and top, heat-soaking everything under there. V8s especially have a lot of internal heat to dissipate. Cylinder temperatures in excess of 1500F aren’t unusual. Keeping the fan operating for a few minutes after shutdown keeps the underhood temperatures from heat-soaking everything under the hood quite so much. Moving air past the engine makes a big difference.
One possibility is that the fans are setup to operate when the engine temperature is above a set point even if the engine is turned off. Some cars are setup that way.
And if that temperature sensor is faulty, the fans will always be on.
And the red wire should be connected all the time, and with the possible temperature sensor fault repaired, the engine operation would be normal.
Of course another possibility is that the previous owner hacked the wiring for some unknown reason.
That’s the way my VW Rabbit worked. I’d have to be careful b/c sometimes I’d be working on a warm engine and the fan would turn on with the keys in my pocket. But my Corolla, the fan is powered up by a relay that is only on with the key in “on”. So my Corolla’s fan always turns off when I turn the key to off.
In '93 I test drove a new '93 Mazda 929, the last year they made it. The car had solar cells in the roof, and fans that would turn on (powered by the solar cells) when the interior got too hot, ventilating the interior. I never saw another setup like it, but I thought it was really cool (pardon the pun). I really liked the car. Unfortunately, my ex wasn’t cool. She nixed the idea… with prejudice.
There have been numerous design philosophies regarding when and how to run cooling fans. There is no “universal” operating setup.
To add a bit of trivia to the issue of cooling systems, there’s a “test” online that states “If you can answer these questions you just might be a mechanic”. There are perhaps 50 questions. I got only one wrong. The question I got wrong was “air cooled engines run hotter than water cooled engines; True or False”. I answered “False”. Their test program replied “Wrong. Air cooled engines run hotter than water cooled engines.”. Clearly the writer of the test never rode in my ‘61 Beetle in the winter. Air cooled engines don’t run hotter. They simply run at temperatures more reflective of the environment around them. Their operating temperatures can’t be controlled as readily as water cooled engines’ temperatures can. If it’s cold out, they run cold… the old Beetles’ engines simply stayed cold all winter. If it’s hot out, they get hotter than water cooled engines.
So I have a fan running I get engines need to cool down but if there is no key in the car and the fan is behind my 3rd row seat what does that have to do with my engine? I recently (this morning) put my 3rd row seats down and tonight my fan on one side is still running. The engine area is quiet. I unplugged the battery as I’m just now finding out some cars still run fans after there shut off. But at the opposite end of the vehicle? 2002 envoy 4wd