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very weird rad fan issue

 
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Old 11 Apr 2013, 08:25 am
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Default very weird rad fan issue

hi everyone,

i'm struggling with this issue for quite some time and I hope that you guys might point me in a good direction since I'm giving up.

here's the 'test case':

I start cold engine (and I mean cold, e.g. overnight cold), drive a bit, temperature reaches about 70C (ca 150F, this read from scanner tool), drive up to traffic lights and stop and the radiator fan kicks in. It runs for roughly 30 seconds and switches off. I drive, stop, same happens. These 'cycles' go for about 2 or 3 times. After that, all is grand - fan only kicks in while I'm in traffic jam and temp goes too much up etc.

A/C is off.

What have been done so far.
1. temp sensor was replaced
2. thermostat was replaced
3. rad fan low & high relays have been replaced
4. A/C compressor pressure switch was disconnected

reputable car carage suspect there is something wrong with the PCM but I can't believe it. It is a very repeatable issue and not just a random hiccup.

what I've done most recently is I took the low rad fan relay out so I don't have to hear this driving me crazy fan anymore Of course that triggered P0480 but I dont care...


Can you think of _anything_ else that could be causing this weird behaviour ?
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Old 11 Apr 2013, 09:13 am
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Default Re: very weird rad fan issue

Bart,

I'm not sure what you problem is except you don't like to hear the fan coming on. The only fan you can here is the HIGH speed. Low speed fan is very quiet. You say "temp goes too much up" but does the temp gauge go way past the half way mark? Is the car overheating?

One thing, you might have had the low speed fan brushes burn out and only have the high. It happens a lot.
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Old 11 Apr 2013, 09:13 am
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Default Re: very weird rad fan issue

If you are hearing the fan running from inside the car then you are hearing the high speed and not the low speed. When this happens are your defrosters on? Because the fans kicks on high anytime the AC comes on. The AC will come on when you have it on defrost. Unhooking the AC would not help as the computer I am sure would kick the fan on thinking the AC is on.
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Old 11 Apr 2013, 09:43 am
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Default Re: very weird rad fan issue

hi guys, thanks for coming back on this.

car does not overheat.
Defrost is not on ( I know it puts A/C on ).

My concern is that first of all, my fan would die earlier because of this frequent runs but secondly sometimes when I'm slowing down to traffic lights and the fan happens to kick in, it brings revs low even to a point where engine stalls.

Reading what you are suggesting I don't understand one thing - if I'm hearing high rad fan, then how come this doesn't happen when low rad fan relay is disconnected ?
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Old 11 Apr 2013, 09:52 am
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Default Re: very weird rad fan issue

Good question. Maybe you can figure it out by seeing this.

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Old 11 Apr 2013, 09:59 am
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Default Re: very weird rad fan issue

I guess I could do the experiment the other way around - pull the high speed relay off and see what happens ?

Question remains though, what could be triggering this weird but repeatable issue...

Last edited by barthek; 11 Apr 2013 at 10:04 am.
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Old 11 Apr 2013, 10:10 am
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Default Re: very weird rad fan issue

You replaced everything I can thing of. While doing all that work, did you reset the computer? Take off the negative battery cable (while there, clean all the cable ends). Step on the brake to get rid of any residual charge. Replace cable. That clears all stored codes and resets everything. Might run rough for a few minutes while the computer learns yours settings. Can't hurt.
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Old 11 Apr 2013, 10:38 am
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Default Re: very weird rad fan issue

Quote:
Originally Posted by CREWZIN View Post
You replaced everything I can thing of. While doing all that work, did you reset the computer? Take off the negative battery cable (while there, clean all the cable ends). Step on the brake to get rid of any residual charge. Replace cable. That clears all stored codes and resets everything. Might run rough for a few minutes while the computer learns yours settings. Can't hurt.
Nope I haven't done this. Will give it a try today. Also I will check if 1st and 2nd fan speeds are working fine by shorting relay sockets...
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Old 12 Apr 2013, 02:22 am
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Default Re: very weird rad fan issue

I would not remove the high speed relay. The high speed prevents overheating as the engine temp rises. Also, jumping the relays is risky because they are tied in to the computer [$$$$$]. Crewzin has info [on this site] on how to test the fan motor by unplugging the fan connector. This isolates the electrical system of the car from the fan.

If the fan noise is excessive, it could be bad bearings or an oak leaf?

The operation of the fan sounds normal, if you're not hearing the fan when it's running on low speed ?
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Old 12 Apr 2013, 03:18 am
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Default Re: very weird rad fan issue

hi pt06
your idea seems to be safer for sure.

sound isn't excessive, but it is annoying nevertheless to know this doesn't operate normally.

according to information I found on this site (that showed a figure from service manual) operation of my fan doesn't seem right - different temperatures when fan kicks in and the fact it does this for a few times and then works as expected.

can you please explain why you believe this is normal operation ?
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