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Old 02-06-2006, 03:19 PM   #1
mbella2000
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Default cooling fan intermittent on the high speed?

Hi all I posted last month about my cooling fan not working correctly after I washed my engine and its been 2 weeks since wash
It actually is intermittent. Ill explain...

When the air is on the fan kicks on low speed but not enough to cool my car off. When im in traffic, the temp goes 2 lines over 200. My car always ran 2 lines under the 200. But sometimes when I park my car and wait, I do hear the "turbo sounding" fan come on...high speed. I look under hood and the fan that is usually real slow when ac is on is now going super fast, and making the high speed fan noise that all vetts make..

most of the time this does not come on but smetimes it does. I checked the fuse box in engine and there are about 4 0r 5 fan relays and 1 fuse. The fuse is fine. When the fan did come on super high speed i found the relay that makes this work, and i put my finger on it and I can hear & feel it click when it comes on and off. Problem is that it also clicks on and off when it just comes on the low speed with a/c on. This 1 relay happenes to be the only relay that clicks either when the super fast fan comes on or when the super slow (same fan) comes on with a/c

My question is can anyone help? Is this relay I am talking about capable of controling my fan to come on 2 different speeds? If I get enough positives from you all, then all I probably need to do is replace that relay. Again this one is the only one clicking when the fan comes on and off, both fan speeds. Now most of the time the slow speed is only coming on and my car is starting to overheat..Any help appreciated. Its driving me crazy.

ps: my fan is fine I hooked it directly to straight power and it spins like an airplane propeller at high speeds
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Old 02-06-2006, 04:06 PM   #2
THXBABY
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There are 3 relays that control the fans. One (I think its #43) closes and both fans run on low speed(fans in series) The other two relays are for High speed only(I think its #44 and #45) When they close it puts both fans in parallel. So in low only one relay is active, and in high all three are active.

Jim
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Old 02-06-2006, 04:08 PM   #3
mbella2000
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thanks.Which one would cause the cars fan to intermittently not come on the high speed most of the time?
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Old 02-06-2006, 04:12 PM   #4
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1 more thing. You stated that when on high all 3 relays are supposed to be on parrrell..why is it thats when it is on high (when it does work) only 1 of the relays clicks on and off. The other 2 do nothing, and the fan is on the high speed at that time...
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Old 02-06-2006, 04:28 PM   #5
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The fan motors are in series on low speed and in parallel when on high speed. When relay #43 get a ground signal from the computer it closes and the fans turn on low. If the temp goes up higher (about 230) then the computer sends a ground signal to relays #44 and #45 and the fan switch to high.

I am not positive on the relay numbers, but if you need the number I will
get it from the manual when I get home and email you.

Jim
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Old 02-06-2006, 05:21 PM   #6
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yes please thanks for ur help. I dont want to replace all relays, I am sure I dont have to do that! Let me know which one or ones control the main relay to come on the high speed
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Old 02-06-2006, 07:47 PM   #7
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All of the fan relays are the same. I had the number turned around though. The #45 supplies power to both fans in low speed and to the left fan on high, the #44 switchs the wiring from
series to parallel, and the #43 supplies the power for the right side cooling
fan in high. I hope this helps!
If you need I could send a copy of the schematic.

Let me know.


Jim

PS Here is the Schematic

Click the image to open in full size.

Last edited by THXBABY; 02-07-2006 at 09:20 AM.
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Old 02-07-2006, 09:35 AM   #8
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thanks so much for your time..ill check them all especially #43!
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Old 02-07-2006, 09:58 AM   #9
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I think that is correct. The right side is the passengers side.

Jim
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Old 02-08-2006, 04:02 PM   #10
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Have you put your DIC on coolant temp to see the actual temp the fans are coming on in low and high? It actually sounds like they might be working fine to me. The fans should come on in low at about 226F and go off at 219F, and shift to high at 235F and back to slow at around 226F. If your AC compressor is on, and the car speed is low (under 35 mph I think), the fans will also come on independent of temp.

It may be possible that your fans have been running the past because the AC was on, but in the cool winter air, the AC compressor might not be on, thus the fans default the their preprogrammed settings.
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Old 02-08-2006, 11:56 PM   #11
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No thanks for the info, but i do know my car and the high speed fan always came on at exactly 2 lines before the 200 temp, not at 235. At 235 you smell an antifreez burning smell because the car is getting hot. I think I will just replace that 1 relay and see what happens, maybe its intemittent. 2 nights ago, I sat in th eparking lot and let the car run parked after coming home and the fan came on again at the 2 lines before the 200 degree mark. It has to be a relay..just dont know which one. But I think they are all interchangable so Ill buy 1 for now...Thanks all
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Old 02-08-2006, 11:56 PM
 
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