Question - Fans on/off frequently while AC is running - DodgeIntrepid.Net Forums - Dodge Intrepid, Concorde, 300m and Eagle Vision chat
 
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post #1 of 11 (permalink) Old 07-03-2016, 01:03 PM Thread Starter
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Question - Fans on/off frequently while AC is running

Hi all,

Thanks for helping earlier with the various quirks of this car. Right now I'm a little confused with what's happening with my fans. Car does not overheat, and I can't seem to pinpoint the issue by searching on the forums.

Not sure if it is coolant temp sensor (my OBD2 scanner still reads temp - would this mean it's ok?) or possibly AC Pressure transducer, but maybe I'm just searching with the wrong terms. I've swapped fuses/relays around and it has not altered any of the symptoms or caused anything else to malfunction.

While A/C is running, fans turn on immediately at high speed, then stay on for 15 seconds, then turn off momentarily. Then they turn back on, and the same thing happens. This is especially noticeable at idle.

If I don't have the AC running, temp gauge gets to the halfway point and then fans will turn on high speed until it gets back down to normal operating temperature - around 3/8 of the way up the gauge.

If anyone has any ideas of what to look for or any additional troubleshooting ideas, please let me know.
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post #2 of 11 (permalink) Old 07-03-2016, 03:44 PM
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See the fan operation table below from the FSM.

Are your fans running at all on low speed? Is that the problem you're seeing?
Attached Images
File Type: jpg Fan operation.jpg (112.1 KB, 11 views)
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post #3 of 11 (permalink) Old 07-03-2016, 04:04 PM
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Also - if your fans are running on only one speed, is it possible that they are running on low speed and you just think it's high speed?

Any codes (by the key dance)?

What year and engine is your car?
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post #4 of 11 (permalink) Old 07-04-2016, 01:49 PM Thread Starter
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Thank you for the suggestions and helpful diagram. Unfortunately, I must have made a mistake when I was swapping relays earlier. Because this time, I swapped the Hi/Lo and the Hi relay and got a P0480 code - Cooling Fan Relay Circuit 1. When I swap them back the code does not return after clearing with my code scanner.

As far as I can tell, the relays are identical. So I am going to buy a new relay and update from there.

In case the info is still needed or would make a difference, I've got a 2002 with the 3.5 non HO engine.
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post #5 of 11 (permalink) Old 07-04-2016, 02:39 PM Thread Starter
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Just swapped in a new relay and fan seems to be running like it should - no longer cutting out after 15 seconds and starting back up again, and no more engine codes when swapping the hi/lo and hi relays with the new relay in the mix. Thanks again (even though it turned out to be a rookie mistake!)
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post #6 of 11 (permalink) Old 07-04-2016, 04:39 PM
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Just so you know, if you pull either relay out of it's socket when the ignition switch is in the Run position, you will get either P0480 or P0481 code depending on which relay you pulled first. I wasn't sure if you had the ignition switch turned off when you pulled the relays and got the code. Also, IIRC, the PCM will activate the signal to the opposite relay to constantly keep the fans on low speed as long as the ignition remains on until the next ignition key cycle *if* it detects that both relays are installed and working.

That may have nothing to do with what you determined, but just saying all that in case you fooled yourself into thinking you have a bad relay when actually you may have caused the code when you pulled the relays.

Otherwise, good troubleshooting!


'98 LXi - Later Concorde gages (black w/ chrome rings)/'99 LX - LHS gages (white) - HIR bulbs

Last edited by peva; 07-04-2016 at 04:52 PM.
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post #7 of 11 (permalink) Old 07-04-2016, 08:34 PM Thread Starter
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Good to know for future reference. For the record, I kept the keys out of the ignition while I was swapping around the relays. I'm just surprised it was only throwing a code when the bad relay was in one of the slots. I suppose it's not the most mysterious electrical issue.
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post #8 of 11 (permalink) Old 08-12-2016, 03:55 PM Thread Starter
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Posting again, as it seems I did not actually solve the problem. Peva, I think you were right that my fan is only running on one speed (high). I hooked up my scanner and monitored the temperature while listening for the fan to kick on. With the A/C off, it only kicked on when the engine temp got to around 230 (just below middle line on coolant gauge) and would stay on until it was lowered a good bit (back to normal operating temp, 3/8 the way up on gauge). At this point, the fans turn completely off. In fact, the fans don't come on while the AC is on, except to go on (I'm assuming) high speed for 10-30 seconds before cutting off again.

I've ended up replacing both of the fan relays in the under-hood fuse box, and I don't see any noticeably bad fuses in that box or the in-cabin fuse box. I'm trying to figure out where to look next and have started reading the FSM and doing some searches. It doesn't seem like it would be the engine temp sensor, as I'm getting reasonable readings on my OBD-2 scanner. No idea how to know if the trans temp sensor is good or bad.

Any further advice would be greatly appreciated.
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post #9 of 11 (permalink) Old 08-12-2016, 08:51 PM
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Buy a cheap new fan assembly from RockAuto and be done with it.

Includes the shroud/motors/fan blades/wiring. Disconnect the electrical connector and unbolt the shroud etc and install the new one.

Last edited by Ronbo; 08-12-2016 at 08:53 PM.
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post #10 of 11 (permalink) Old 09-11-2016, 04:58 PM Thread Starter
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Thanks for the suggestion. It did not occur to me that the fan would fail in like this. I replaced it with a new one a while back and has been holding up for about a month.
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post #11 of 11 (permalink) Old 09-11-2016, 08:38 PM
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Another suggestion: If you have the stock fan assy, there are two relays mounted in the top center of the assy.
They are the same relays as those used in the PDC. They look different because they are waterproof.
If you have a pick-n-pull nearby, you can grab some relays from the yard and swap them with yours and see if you get any better results.
I would grab the relays out of the pdc just because they are easier to get to.

If the results are good with those relays, then you can go back and grab a handful of the waterproof relays -- or buy brand new ones.

Best of luck with you project!
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