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Join Date: Jul 2003
Location: Boston, Ma
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Random question about cooling fans.
My cooling fans stop when i turn the engine off. Is this the proper behaviour or should they run for a while with the ignition off (assuming the car is hot enough to warrant it). I notice that modern cars do this, but i'm not sure what year they started this.
N.
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89 944 Turbo 115k miles, Stock 96 Range Rover 4.0 SE 130k miles. 84 944 170k miles, FR Wilk Chip, Sold. "Don't listen to me, I dont know what i'm talking about" |
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06-22-2004, 09:10 AM
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One of the fans should "idle" (run at a reduced speed) for a while IF the radiator is hot. This is part of the temp switch circuit.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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06-22-2004, 09:15 AM
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Hmmm mine doesn't.... I wonder if this is connected to my evil, fuse eating AC, which after further investigation might not be that evil after all, as the fuse blows when the cooling fans come on...
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89 944 Turbo 115k miles, Stock 96 Range Rover 4.0 SE 130k miles. 84 944 170k miles, FR Wilk Chip, Sold. "Don't listen to me, I dont know what i'm talking about" |
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06-22-2004, 09:22 AM
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If either of the fans fuses blow it's because the fan is bad. With the key off and the car cold reach down and spin the fans. One may be hard to spin. This means the bearing is bad. Could also be worn out and one of the brushes is making intermintent contact.
The 25 amp fan fuse is also the fuse for the A/C clutch on the compressor. Could have a bad clutch or the wire could be grounding out to the engine.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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06-22-2004, 09:32 AM
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entertaining the idea
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I had the same problem last year, and it was a bad fan that kept blowing the fuse. It was difficult to turn as SoCal said. After I replaced the fan, I found that the relay was bad as well.
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There are some who call me... 'Tim'. a well set-up 1983 Guards Red 944 |
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06-22-2004, 09:40 AM
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Now you asked, :-) this is the full situation.
Fuse #6 blows when i turn on the AC, it also blows when the cooling fans come on. PO had this problem and it went away when he replaced the thermoswitch(1 year ago). When i picked up the car it generally blew after 30-40 mins, but now it blows all the time. Fans are also a year old ( I will test then tonight for ..erm.. turnability), and the AC clutch if i'm testing it correctly only has 3.9ohms resistance, which i believe is normal. ( i test by unplugging the single wire that "appears" to connect to the clutch and connecting my multimeter between that and a ground) Thats about it...
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89 944 Turbo 115k miles, Stock 96 Range Rover 4.0 SE 130k miles. 84 944 170k miles, FR Wilk Chip, Sold. "Don't listen to me, I dont know what i'm talking about" |
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06-22-2004, 09:43 AM
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the front bearing on the early three bladed fans does not have seals. These will eventually rust up and seize. The six bladed fans have sealed bearings in them. I have yet to hear of one seizing up.
If the fan does seize up the current draw will play havoc with the rest of the circuit till the over sized fuse blows.
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Hugh - So Cal 83 944 Driver Person NOT a 'real' Porsche -- Its Better!!!! When was the last time you changed your timing and balance belts and/or cam chain and tensioner? New Users please add your car's year and model to your signature line! Never break more than you fix! |
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06-22-2004, 09:44 AM
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Quote:
When i unplug both fans and the thermoswitch, fuse #6 still blows, i'm guessing this rules them out as the main cuplrit? Back to the wiring diagram....
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89 944 Turbo 115k miles, Stock 96 Range Rover 4.0 SE 130k miles. 84 944 170k miles, FR Wilk Chip, Sold. "Don't listen to me, I dont know what i'm talking about" |
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06-22-2004, 08:15 PM
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Location: Virginia/Ohio
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The fans and temp sensor are pretty easy to check. Thermofan switch should close when the engine is hot (197 deg F for a stock switch, labeld in celsius). A thermocouple in the coolant flow will give you a precise reading, but this is not necesarily a requirement. The fans should turn with 12V DC applied to them (be sure to limit the current to prevent blowing the fan).
Sounds like they are fine though. Try checking the relays. I don't know much about the AC circuit, though, so someone else has to take that.
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White 1985/1 944 --my first car --limited slip differential --cross drilled rotors --omnimagnum high-energy ignition --CB equipped --laptop installed, seeking GPS chip --keep the socks away from my car |
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06-22-2004, 09:44 PM
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1983 Porsche 944 2.5 liter
1983 Porsche 944 2.5L
