My wife drives a 1999 Chrysler Town and Country Limited with the 3.8 V6.
Recently the cooling fan has been running even with the ignition tuned off. She first noticed it a few days ago when she heard a “whirring” sound coming from under the hood when she went to unlock the door. A day or two later she noticed the same thing as she was getting into the van after unlocking the door. Tonight she got home, got out, locked the van, and came into the house. 10 or 15 minutes later we both heard a sound coming from the carport and went to investigate. It was the van; both cooling fans were running. I had to disconnect the battery to get it to stop.
Now here’s the kicker. A month or two back she called me from work, telling me her van wouldn’t start. I went to where it was parked and tested the battery—it was dead. It was needing replaced so I went ahead and bought a new one, and as soon as I hooked it up the fans kicked on; again the ignition was off. I figured this was what had drained the battery. Snooping around on Google I learned that this is usually a stuck relay. I bought a new relay and replaced it, and all seemed well until a few days ago.
Now, the relay I changed is the relay that is bolted to the frame near the radiator, not a plug-in relay that shares space in the fuse box. Tonight I unplugged that relay (the one in the fuse box) as the fans were on and… nothing. The fans didn’t stop but quite happily kept on spinning at full speed. I had to completely unhook the battery to get them to stop.
So. What the hell is going on? Did I get a bad relay from the parts house (a local place, not the dealer)? If not, what could be the trouble? Computer problem? And even so, why won’t pulling the relay in the fuse box stop the fans (I double checked and yes, I pulled the right one).
Given time, does it stop? I’ve had fans run 15 minutes or so after the car is stopped. They are electric and run off a thermostat. Possibly that is failing. Or you are running your engine very hot, check the coolant level and if you have a water temp readout in the dash or a gauge, make sure it is reading normally.
The first time it did it, when I had to change the battery, it was dead cold. The most recent times have been between 15 mins and 2 hours after shutting it down. So I don’t think engine temp is related.
The wiring diagram shows the radiator fan relay power coming straight from the battery rather than through the ignition switch, and the operating signal for the relay coming from the PCM (main computer). The PCM function here may or may not be dependent on the ignition being switched on; my information doesn’t say one way or the other, so I can’t tell if the fan sometimes running after shut-off is clearly a fault or not.
If the fan is running when it shouldn’t be, it could be due to a faulty fan relay or PCM, and if it’s meant to run with the ignition off a faulty engine temperature sensor or A/C high pressure switch.
I haven’t seen any indication of a radiator fan relay in the fuse box. What EXACTLY is the description/label for the relay you unplugged?
I just went and looked at the fuse box, and the relay is marked BLOWER MOTOR RELAY which, now that I think about it, might be the heat/AC fan—obviously my first assumption was that it was for the cooling fans. If it indeed only has the one relay then that relay is essentially brand new.
I’m not at all looking forward to changing the PCM. If I recall they need to be installed by the dealer because they need to be programmed, yes?
Fan still running? Issue is not the PCM, most likely, bad relay, unless you got a battery hot line shorted to the PCM fan signal line.
Sounds like your car is one of those where the PCM controls nearly everything?
So engine temp and AC signals go into PCM, PCM then sends out a single signal to the trigger side of the relay?
If it goes off when PCM gets unplugged, it still may not be PCM
PCM may be getting bad data from one of the sensors, a lot of newer cars with run the fans for a short bit after you kill the ignition if its getting a certain temp signal, then the fan runs for some pre-programmed amount of time.
I liked it better when the PCM simply ran the ignition, and triggered the fuel injectors
and pump relay.
No i lie, i liked it better when the PCM didn’t exist
It really could be a circuit fault somewhere. I had a 2004 Neon, and on that car if you removed the cooling fan relay while the car was on, the PCM would sense that as a circuit fault, set a code, and turn the fans on full blast (by design.). Is the check engine light on?
Even if it isn’t, you can read codes on a Chrysler vehicle like so. Get in the car, insert the key into the ignition, and (without starting the car) turn the key from OFF-RUN-OFF-RUN-OFF-RUN with about a 1/2-second cadence. Any stored codes will show on the odometer, followed by “d0nE.”
The check engine light is on, but it’s been on for… 3 years? I had to have the bottom end of the engine rebuilt ~18 months ago and the shop who did it said not to worry about it. I know the light means something, obviously, but since the van continued to drive and function flawlessly I didn’t worry about it.
I tried the ignition switch code test. Didn’t work, but that may be an ID10-T problem. When I went out to do that test just now (8am in the morning, so the engine was cold), the fan kicked on as soon as I hooked up the battery, then shut off after ~10 seconds.