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E34 (1989 - 1995)

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  #1  
Old 08-21-2012, 04:03 AM
GlueBall GlueBall is offline
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Exclamation Condenser fan runs when A/C compressor runs

Whenever the A/C compressor switches ON, the condenser fan comes ON and stays on until compressor cycles OFF, irrespective of speed. Mechanics tell me that this is normal. But why would the fan need to run at 200kph...? Isn't there supposed to be a thermal switch to regulate power to condenser fan? (1989 525i E-34)
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  #2  
Old 08-21-2012, 04:58 AM
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Costa Costa is offline
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Why are you driving 200k with the A/C on? that's the question you should be asking yourself

Edit: how are you driving 200 k in an M20.




















LOL
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  #3  
Old 08-21-2012, 09:23 PM
paperplane94 paperplane94 is offline
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It IS capable.

Just a matter of getting there.
Anyways, he never said he was going 200 KPH. He was giving an example...


The condenser fan has two speeds. There is a thermal switch on the side of the radiator that switches on the condenser fan low/high. But, once you turn on the A/C, the switch is bypassed so it will run on its lowest speed always. Your mechanic is right, what's wrong with it running all the time?
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Old 08-22-2012, 12:07 PM
GlueBall GlueBall is offline
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When on the highway, and traffic permitting, I drive as fast as it will go, which in my case ('89 E-34 525i) is 215kph on 97 octane fuel. . . not because I'm in a hurry, but just for the thrill of speed. I drive with the A/C on most of the time in the tropics, just 3 degrees north of the equator. Obviously, it's a BMW design flaw to run the electric condenser cooling fan whenever there is enough cooling air from the slipstream.
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Old 08-22-2012, 03:27 PM
paperplane94 paperplane94 is offline
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Yeah, the Japanese thought to turn it off at certain speeds I guess.
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  #6  
Old 04-09-2013, 01:53 PM
mdl4real mdl4real is offline
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I have a 03 745li my a/c only works sometimes if it does come on its only for a few minutes then turns off I have replaced the blower motor and the part that looks like metal spikes under the dash has been up graded to a part that looks like a computer chip also I'm in the process of replacing the condenser fan because it's making a rattling sound when the a/c does come on......does anyone know What the problem could be
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  #7  
Old 04-09-2013, 07:45 PM
upallnight upallnight is offline
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Quote:
Originally Posted by Costa View Post
Why are you driving 200k with the A/C on? that's the question you should be asking yourself

Edit: how are you driving 200 k in an M20.
Drove it off a Cliff. LMAO

Last edited by upallnight; 04-09-2013 at 07:49 PM.
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  #8  
Old 04-10-2013, 05:48 AM
snowsled7 snowsled7 is offline
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Quote:
Originally Posted by GlueBall View Post
When on the highway, and traffic permitting, I drive as fast as it will go, which in my case ('89 E-34 525i) is 215kph on 97 octane fuel. . . not because I'm in a hurry, but just for the thrill of speed. I drive with the A/C on most of the time in the tropics, just 3 degrees north of the equator. Obviously, it's a BMW design flaw to run the electric condenser cooling fan whenever there is enough cooling air from the slipstream.


Then 99% of the cars on the planet with AC share that design flaw It is normal, and running that electric fan doesn't hurt a thing. What is the concern?
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  #9  
Old 04-10-2013, 09:41 PM
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supertech777 supertech777 is offline
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Quote:
Originally Posted by Costa View Post
Why are you driving 200k with the A/C on? that's the question you should be asking yourself

Edit: how are you driving 200 k in an M20.




















LOL
^ this +1

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  #10  
Old 04-11-2013, 12:10 AM
imae34driver imae34driver is offline
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Mein Auto: 1995 540i SPORT /6 spd
Just to play Devils Advocate - hehe -

I once had a car come in the shop.. think it was a ford.. anyways.. Damn thing only overheated on the freeway.. WTF right?

could not figure it out.. after 70 mph it just gets hot.. not rpm related.. not load ... not at a light or at a stop on a hot day..

Damn things fan stayed on, and after 70 mph the electric fan being to slow at speed actually became and obstruction to the flow of natural air thew radiator and created a shield of hot air blocking cool air..

Took me all day scratching my head cussing.. unplugged it and it only got a little hot at lights.. new relay., all better..

When you see the fan come on, you assume its good.. Wrong!!

Anyways - Point being, if i were to drive my car fast enough, it may cause air restriction and overheat.. i have heard delimited the 540i/6 hits 181 with infinite room.. ad boost a lower gear ratio.. do 200 mph +????

may still not be enough to cause a problem.. but the very unreal possibility is there that he wants to do 210 mph with the a/c on. and this could pose a problem.. hahahahaha

How's that for a resin?


fck jdm / fck honda

Last edited by imae34driver; 04-11-2013 at 12:12 AM.
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  #11  
Old 04-11-2013, 01:01 AM
allenbee allenbee is offline
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Op has clarified that this is 200kmh i.e. 125mph.

And the faster you drive, the faster your pump spins, the more quickly heat is circulated out to the rad and back, the higher speed of airflow means greater cooling per second. The confluence of this is normal engine temps.

You can near redline your car indefinitely on the road. Temp will be normal, provided it is mechanically sound in all relevant aspects.

Last edited by allenbee; 04-11-2013 at 01:11 AM.
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  #12  
Old 04-11-2013, 04:29 AM
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TWard TWard is offline
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The reason that the electric fan is on is to pull heat from the condenser. The only way that a condenser works is that if air is going across it, and a lot of it. The reason you need some much air going through the condenser is because inside it there is a state change happening with the refrigerant. It is change from a compressible gas from the compressor into a liquid inside the condenser. Even though the temp doesn't drop too much inside you lose a ton of latent heat. allowing it to change from a gas to a liquid.

That is a normal operation there is no problem.
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  #13  
Old 04-11-2013, 06:18 AM
allenbee allenbee is offline
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I'm pretty sure that the auxiliary fan's airflow impedence risks were properly tested by BMW under all appropriate conditions including extreme ones. Obviously condenser cooling by fan is not necessary at high road speeds, they probably leave it on because it makes no practical difference either way.

How do you know that the fan is running at 125mph ? I don't think your E34 is so quiet at that speed for you to pick up the noise.
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  #14  
Old 04-11-2013, 08:21 PM
manuelwindows manuelwindows is offline
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Mein Auto: 1994 530i, 1977 320i
I'll never forget when a Chevy Blazer tried to keep up with me on a lonely stretch of Georgia highway, I was running at about 125-130 mph in an '85 535i. All of a sudden that Blazer starts smoking from the engine compartment and drops off to the side of the road. And isn't it for those moments that we own these cars? :o)

I actually didn't think a Blazer could even go that fast but it turns out that it can but only for about 5 minutes.
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