Cooling system Problem
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Joined: Mar 2000
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Cooling system Problem
Hey there,
I've got a 92 100 with the 2.8 and have been having a problem with the cooling system lately. It seems that
1. The cooling fans always run, even just after starting on a 20 degree day
2. According to the dashboard gauges, the water (radiator) temperature usually reaches operating temperature before the oil temperature which seems counterintuitive.
Does anyone out there know of a temperature sensor/switch which would control both the fans and the flow of coolant into the engine? I've been reading the site for a while, this place is great.
Thanks,
Dave
92 100 with 108K
I've got a 92 100 with the 2.8 and have been having a problem with the cooling system lately. It seems that
1. The cooling fans always run, even just after starting on a 20 degree day
2. According to the dashboard gauges, the water (radiator) temperature usually reaches operating temperature before the oil temperature which seems counterintuitive.
Does anyone out there know of a temperature sensor/switch which would control both the fans and the flow of coolant into the engine? I've been reading the site for a while, this place is great.
Thanks,
Dave
92 100 with 108K
Audiworld Junior Member
Joined: Jul 2000
Posts: 252
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the coolant flow out of engine into radiator is controlled by the usual thermostat...
which is a mechanical, not electrical device (a substance in the thermostat expands as it heats and opens the route for engine coolant to enter radiator.)
The electric fan is controlled by completely separate sensor(s). when that sensor experiences a certain temp. it closes switch and powers the fan. But most audi's have a number of sensors/switches that have the capacity to turn fan on. For example. usually any time the A/C is on, the fan turns, regardless of engine temp.
The fact that the 2 guages don't show operating temp at same time may just represent a more responsive sending unit on one, or, perhaps just different or inaccurate guage calibration. I would tend to ignore that and not see it as a problem. Obviously, the 2 liquids can't be too far apart in true temperature.
As far as the fan turning on, you're wasting electricity, and additional wear and tear on fan, but otherwise it's not a serious problem. You will need to tediously track down the schematic, and item-by-item look at each circuit to figure which sensor is turning the fan on erroneously.
Good luck!
The electric fan is controlled by completely separate sensor(s). when that sensor experiences a certain temp. it closes switch and powers the fan. But most audi's have a number of sensors/switches that have the capacity to turn fan on. For example. usually any time the A/C is on, the fan turns, regardless of engine temp.
The fact that the 2 guages don't show operating temp at same time may just represent a more responsive sending unit on one, or, perhaps just different or inaccurate guage calibration. I would tend to ignore that and not see it as a problem. Obviously, the 2 liquids can't be too far apart in true temperature.
As far as the fan turning on, you're wasting electricity, and additional wear and tear on fan, but otherwise it's not a serious problem. You will need to tediously track down the schematic, and item-by-item look at each circuit to figure which sensor is turning the fan on erroneously.
Good luck!
AudiWorld Super User
Joined: Mar 2000
Posts: 9,281
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Everything sounds normal to me...(more)
....As "mel g" said there is nothing electrical that controls both flow and fan. The flow of water is controleed by the thermostat and the radiator fan is controlled by the thermoswitch (at the bottom of the radiator)!!
The water will warm up faster than the oil because it's thinner. It's also the sole puropse of the water to keep the engine cool while the oil is "primarily" for lubrication. The water should warm up faster....when it's doing it's job correctly!!
As for the radiator fan...you have an automatic climate control, right?? If you don't want your raditor fan to run all the time turn it off of "Auto". If you flip it to "Econ" (and possibly "Bi Lev") it should shut the rad. fan off (until it's needeed for the heat). The only reason the fan is on is for the A/C. If you have it on "Auto" the fan is going to run constantly!!
From what you explain I don't see any problems with your car. If I misinterpreted something please let me know (or incorrectly guessed your climate control)!!
HTH!!!
---
Andrew
90 80q
91 90
95 90q
The water will warm up faster than the oil because it's thinner. It's also the sole puropse of the water to keep the engine cool while the oil is "primarily" for lubrication. The water should warm up faster....when it's doing it's job correctly!!
As for the radiator fan...you have an automatic climate control, right?? If you don't want your raditor fan to run all the time turn it off of "Auto". If you flip it to "Econ" (and possibly "Bi Lev") it should shut the rad. fan off (until it's needeed for the heat). The only reason the fan is on is for the A/C. If you have it on "Auto" the fan is going to run constantly!!
From what you explain I don't see any problems with your car. If I misinterpreted something please let me know (or incorrectly guessed your climate control)!!
HTH!!!
---
Andrew
90 80q
91 90
95 90q
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Re: the coolant flow out of engine into radiator is controlled by the usual thermostat...
Thanks Mel,
From your post it seems that I just need to replace the thermostat which will prevent the coolant in the radiator (which is constantly being cooled by the fan) from entering the engine before it should.
-Dave
From your post it seems that I just need to replace the thermostat which will prevent the coolant in the radiator (which is constantly being cooled by the fan) from entering the engine before it should.
-Dave
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Re: Everything sounds normal to me...(more)
Thanks for the quick responses
I don't think that everything is normal because I have noticed poor fuel economy in cold weather since I first noticed the problem which I attributed to the engine not reaching full operating temp (I should have fleshed this out in my first post). Also, I have the manual climate control and the fans run regardless of the settings.
thanks,
dave
I don't think that everything is normal because I have noticed poor fuel economy in cold weather since I first noticed the problem which I attributed to the engine not reaching full operating temp (I should have fleshed this out in my first post). Also, I have the manual climate control and the fans run regardless of the settings.
thanks,
dave
AudiWorld Super User
Joined: Mar 2000
Posts: 9,281
Likes: 1
Re: Everything sounds normal to me...(more)
If you have the manual climate control then you do have a problem with your radiator fan (unless your "A/C" or "REC" button is pushed down)!!
It could be that your A/C button won't "release"...I have had this problem before!! Even with the button in the "off" position the A/C was still on...that was in my I5. It was easy to diagnose in that car because it runs a different fan!! To fix it I had to replace the climate control unit...although I probably could have just fixed the button (being lazy)!!
You may be getting the same thing!!! If the A/C button comes out okay then you should move to the thermoswitch!! Changing your thermostat is not going to help your fan problem!!
Good Luck!!!
---
Andrew
90 80q
91 90
95 90q
It could be that your A/C button won't "release"...I have had this problem before!! Even with the button in the "off" position the A/C was still on...that was in my I5. It was easy to diagnose in that car because it runs a different fan!! To fix it I had to replace the climate control unit...although I probably could have just fixed the button (being lazy)!!
You may be getting the same thing!!! If the A/C button comes out okay then you should move to the thermoswitch!! Changing your thermostat is not going to help your fan problem!!
Good Luck!!!
---
Andrew
90 80q
91 90
95 90q
AudiWorld Expert
Joined: Jun 2000
Posts: 29,356
Likes: 1
Sounds like your A/C systems on?
Anytime your a/c compressor is on the fans can and will run to regulate the refrigernat system pressure.
If you a/c is switched off, and the fans comes on with the ignition key, them you probably have an a/c high pressure switch gone bad.
Turn off the a/c and let us knowthe result.
If you a/c is switched off, and the fans comes on with the ignition key, them you probably have an a/c high pressure switch gone bad.
Turn off the a/c and let us knowthe result.
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Re: Everything sounds normal to me...(more)
Thanks All,
The fan does indeed run regardless of the AC setting, and otherwise the AC works fine (it works when its on and stops when its off). So.... I think I'll start with the quick and easy and replace the thermostat first, see if my MPG improves and then if not look into the electronic sensors. It doesn't seem to be worth fixing the fans if they are not causing any other problems.
-Dave
The fan does indeed run regardless of the AC setting, and otherwise the AC works fine (it works when its on and stops when its off). So.... I think I'll start with the quick and easy and replace the thermostat first, see if my MPG improves and then if not look into the electronic sensors. It doesn't seem to be worth fixing the fans if they are not causing any other problems.
-Dave
