Dear Car Talk.
My daughter has a 2009 Honda Civic 4dr sedan with AC and about 85,000 miles on it. Several weeks ago after returning from work, she called and said the radiator fan was still running even after she shut the engine off. Having had some experience in maintaining cars for many years I thought a moment and said, “The fan will run until the engine cools down.” The next morning the battery was dead. (Lost major points on that one.)
I took her car to my trusted mechanic who spent three days trying to duplicate the problem to no avail. I returned the car to her and it ran ok for another week. Meanwhile, I checked online and found several UTube videos describing this problem for this model car, which pointed to the Fan Control Relay.
When the problem recurred, I took it back to my mechanic who, after some persuasion, replaced the relay. Several days later, the fan stayed on again.
I took it to a Honda dealer who acted as though he’d never heard of this problem before, He kept it for three days. He couldn’t reproduce the problem but suggested I replace the fan control relay (which I told him I’d already done).
Several days later, she called and said both fans were on. I took her car home and pulled the fan control relay, both fans stopped.
I left the car was outside all night. (It gets up to the 80s in the daytime and down to 60 at night.) The next morning, I put the relay back in and both fans turned on. I drove the car 5 miles to my mechanic again, turned off the engine and opened the hood: Both fans sat idle with malicious grins on their faces.
Oh Car Guru, what do I do next?