2000 dodge caravan 3.0 radiator fans not coming on
nwg916
11-04-2013, 08:20 PM
So my radiator fans were staying on until my battery died and my car was completely cooled down and off. I was told it was a sticking relay so I replaced it and the fans still won't come on. I unlpugged the coolant temp sensor and the fans came on so I know its not the motors or anything. Could it be the coolant temp sensor? Just want to get some opinions before I go out and buy one.
RIP
11-07-2013, 02:45 PM
Do they come on when the A/C is turned on?
nwg916
11-09-2013, 05:22 PM
Do they come on when the A/C is turned on?
Well I ran the car for about 20 mins to let it get up to normal operating temperature, still no fans. Then I turned the A/C on for about 5 minutes and they still didn't come on. The only time they have came on was when I unplugged the coolant temp sensor and the computer automatically turned the fans on. So I'm thinking maybe the coolant temp sensor isn't sending the temperature information or whatever to the pcm and the fans aren't turning on. Could this be it? I'm not really sure.
Well I ran the car for about 20 mins to let it get up to normal operating temperature, still no fans. Then I turned the A/C on for about 5 minutes and they still didn't come on. The only time they have came on was when I unplugged the coolant temp sensor and the computer automatically turned the fans on. So I'm thinking maybe the coolant temp sensor isn't sending the temperature information or whatever to the pcm and the fans aren't turning on. Could this be it? I'm not really sure.
RIP
11-09-2013, 07:05 PM
Reason I asked is the cooling fans should come on as soon as you turn on the A/C. Two things make the fans turn on. Engine temp via the ECT sensor and A/C pressures sensed by the pressure switch. If neither turns them on you either have a wiring problem from the PCM to the relay, your relay is bad, or the PCM is bad. That's the typical scenario. Yours isn't typical because you disconnect the ECT sensor and they spin up just fine. That at least says you don't have the wiring or relay issue. I'm not prepared to say you need to fork over the bucks for a new PCM though. Seems like I've read about this before but I don't have the answer. Anyone else?
jpb53
11-12-2013, 09:49 AM
This might help.
http://www.automotiveforums.com/vbulletin/showthread.php?t=909708
http://www.automotiveforums.com/vbulletin/showthread.php?t=909708
Bill Grissom
11-22-2013, 02:28 PM
jpb53,
Thanks. Very useful link. I also wondered why my fans didn't come on, even when the AC compressor actuated. I assumed the engine controller decides when to turn them on and how much and the link shows it is dependant on several sensors and the fan is infinitely adjustable (PWM control). In many cars, the radiator fan automatically runs whenever the AC compressor is on, thus the confusion. I might have to bugger with the AC pressure signal since 250 psig is pretty high for the HC refrigerant I switched to.
Thanks. Very useful link. I also wondered why my fans didn't come on, even when the AC compressor actuated. I assumed the engine controller decides when to turn them on and how much and the link shows it is dependant on several sensors and the fan is infinitely adjustable (PWM control). In many cars, the radiator fan automatically runs whenever the AC compressor is on, thus the confusion. I might have to bugger with the AC pressure signal since 250 psig is pretty high for the HC refrigerant I switched to.
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