The vehicle is 1999 Chrysler Town and Country Limited with the 3.8L V6.
A while back my wife called me from work and reported that the battery in her van was dead. She had tried to leave for lunch and the thing wouldn’t start. I went and jump started it, but the next morning it was dead again. So I went to Mega-Lo-Mart and got a new battery, installed it… and the radiator fan immediately came on. I double checked that the key was turned off (it was), and then disconnected the battery.
Google told me it was likely a “cooling fan relay” that was mounted next to the radiator. $70 later I had installed a new one. And… the problem persisted.
So to be clear, I turn off the ignition, take the key out, and yet the cooling fans are still running intermittently. I’ve locked the doors and walked away, and it’s still happening. Sometimes they kick on immediately, sometimes it takes a minute or two. Engine temp seems to have no effect at all. I disconnected the battery and haven’t messed with it since.
I have absolutely no idea how to even begin diagnosing this. Anybody have any ideas?
Also, a couple of people have told me this is normal.
No, it’s not. The fans running with the ignition on (but not the engine running) can happen with electric fans with temperature sensors. But running with the ignition off, key out of the ignition, car locked, etc. is not normal.
there’s a fault somewhere in the cooling fan relay circuit. You’re going to have to start probing wires and tracing circuits.
edit: just to clarify, on these Chrysler vehicles, they are designed so that the cooling fans turn on full if there’s a problem in the control circuit. this is kind of a “fail safe” way to make sure a circuit failure doesn’t lead to engine overheat.
You sure? I have heard a number of unoccupied locked up cars with their fans running. Should turn off in a minute or two though. I believe my 1989 Nissan did this as well.
I just spent a few minutes looking this up (since it is normal in my experience as well). For the 1996-2000 Chrysler Town & Country series, this is not normal and is a known and somewhat common problem. The location of the fan relay is conducive to failure.
Yeah, I’ll amend my post and say it’s not normal for this vehicle.
All my googling says it’s a fan relay, but even with a new relay the problem persists. I have no desire to start tracing an intermittent electrical circuit failure; if that’s my only option it may be time to part with it. It’s our 3rd vehicle and not vital, but I’d like to get it running reliably again rather than scrap it.
I noticed my car doing the same thing last month (fan running for an unusually long time after turning off ignition, when the car and outside temperature were not that hot). Two days later while I was driving, the temperature gauge needle dropped all the way to “C”'and I smelled coolant— which, as it turned out, had sprayed all over the underside of the hood from a broken gasket somewhere. I had to get it towed and the thermostat replaced. </anecdote>
It could be your temperature sending unit. Normally, this would also make the temperature gauge in the car peg, but if there is a separate unit for the cooling system, or some problem that happens only when the ignition is off, then what is happening it that the temperature sending unit is telling the cooling system (probably the water pump in addition to the fans) that the engine is hot, and needs to be cooled. And it keeps telling the system this, even when the engine is actually cold.
I have no idea where the sending unit is in your car, but if it is easy to get to, then it is probably easy to replace. It is probably a cheap part too, and so just as a “Let’s try this and see,” wouldn’t hurt.
Another thing is that if the thermostat is stuck closed, the engine really is hot, and not getting cooled, in spite of the cooling system being on, although this should peg your gauge as well, unless it is just closing prematurely. These are usually cheap parts too, and easy to replace, and need periodic replacing, so if it hasn’t been done in a while, just go ahead and do it.
A long shot is that there’s a lot of junk and air in the cooling system, and the temperature sending unit is located some place where there tends to be an air bubble. This is an old car. When did you last do a flush and fill on the radiator? If it’s overdue, do one.
While the problem is occurring, see if the relay “trigger” wire (terminal 2, light green wire w/ dark blue stripe) is grounded. If so, the PCM (main computer) may be faulty. Before condemning it, check the operation of the coolant temp sensor as suggested by Rivkah.
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