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Discussion Starter · #1 ·
I have a rover200 1.8 with a/c. I live in Greece and since we are close to summer the temparature has rosen a bit..at about 30C degrees..My point of course is not about the climate in Greece, but lately i ve noticed that car's cooling fan and a/c fan engage at high speed quite often. Obviously this is due to the fact that the temperature is higher than in winter time, BUT as far as i can remember at the previous summer, and the summer before that, no matter how often i used the a/c, no matter how hot it was outside (40C degrees) the car had the cooling fans operating at slow speed even with the use of a/c. And this is more obvious during the daytime while the temperature is higher than at night.
So if i remember correctly and the car didn't operate in the past at high speed, even hotter climate, could this be an indication that the thermostat isn't working properly, and take longer to open/close? or sth else?
 

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The fan shouldn't really be coming on at all when the car is moving as air flowing through the grill is enough to cool the engine.
How do you know the fan is cutting in at high speed, you must have very good ears?
 

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Discussion Starter · #3 ·
you can definately tell the difference between fan slow speed and high speed.. should i guess that you don't have a/c since the a/c fan is that makes great difference when is engaged on high speed.. not to mention that when fan engages at high speed you notice at idle a little rev change..So i can definately tell when cooling fans are operating at high speed..
the question is why..? i doubt that air coming through grille is able to cool engine especially if you face traffic, heat, and other difficult conditions..

p.s. remove with the engine operating the the brown plug from the coolant temperature sensor, and you ll notice how different the fan sounds at high speed..
 

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Ok just to repeat.
The fan is simply there to cool the engine when the car is either stationary or moving slowly in traffic. It shouldn't if ever kick in when the car is moving under normal driving conditions. There is more than enough cool air provided to cool the engine from airflow through the grill.

If the fan is kicking in regularly while on the move then there is a problem with the cooling system. Either the temp sensor is faulty, waterpump isn't working properly or maybe the thermostat is jammed. There are also other possibilties such as partially blocked radiator or even air in the system.
 

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Discussion Starter · #5 ·
the thermostat was what i thought of in the first place..the temperature sensor was replaced last year, and the waterpump has never been replaced (103.000km)..
in case i wasn't clear, i can't notice the fan while moving, but i can notice it when i m stuck in traffic jam, or waiting for a traffic light to become green..or sth like that. Sorry if it sounded that i noticed high speed while running the car
 

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With an A/C installation the fans are connected in series and run all the time at slow speed when the air con is switched on.

If the coolant temperature continues to rise the fans are switched to parallel and run at high speed, I think this only happens if the coolant is above 112 deg. C.
 

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On an older car like yours it could be any of the things mentioned before. If the waterpump is going it should leak, but you didn't mention this so I think it could be a blocked radiator, or one missing lots of metal fins. If it was the thermostat you would notice the gauge reading higher than before, so I guess it isn't this.
 

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Discussion Starter · #10 ·
With an A/C installation the fans are connected in series and run all the time at slow speed when the air con is switched on.

If the coolant temperature continues to rise the fans are switched to parallel and run at high speed, I think this only happens if the coolant is above 112 deg. C.
totally agree.. the case is, that even with a/c off after a while (at daytime) 35C degrees i notice that fans engage on high speed..which didn't happen last year during summer time..so sth seems not to be as it was..but what!?
 

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Discussion Starter · #11 ·
On an older car like yours it could be any of the things mentioned before. If the waterpump is going it should leak, but you didn't mention this so I think it could be a blocked radiator, or one missing lots of metal fins. If it was the thermostat you would notice the gauge reading higher than before, so I guess it isn't this.
no leaking.., no temperaure rise.., air lock or blocked radiator? could it be that the thermostat find difficult to open/close?
 

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no leaking.., no temperaure rise.., air lock or blocked radiator? could it be that the thermostat find difficult to open/close?
yes it could, but I would think that you would see a higher temperature on the gauge than last year.

Which temperature sensor did you change, the one for the gauge, or the one for thr ECU?
 

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Discussion Starter · #13 ·
both sensors have been changed..not at the same time but definately both where changed about a year and a half ago..
news are, that fans engaged at high speed even at night that the temperature is lower than during the daytime.. So sth definately isn't correct..but what..?
 

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Discussion Starter · #14 · (Edited)
sth that i remembered now, first time that i noticed the fan speed case, was 1,5 month ago when i was stuck at traffic jam for about 3,5 hours with engine on all this time..

edit: is there any sensor on the radiator? or on the fan of the radiator? apart from the two mentioned..
 

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Discussion Starter · #16 ·
the expansion tank cap is about one year and a half old as well because i had replaced both expansion tank and cap with the facelift's with the coolant level sensor..
 

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Discussion Starter · #17 ·
how likely would it be to have a failure on the a/c relay module, so that sometime to operate on slow scale and others on high scale? since it's that which defines which scale would be activated..
 

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Discussion Starter · #20 ·
i think now, i can start worrying again..

i took the car to the garage for a couple of checks.. (oil leak from camshafts etc..) so i thought why not check it from testbook to see what is going on with temperature..
left the car running..until it reached 102C when fan speed 1 engaged and after a while turned to fan speed 2!
checked multifunction unit..couple of plugs, fuses.. and performed an overall check again..
car reached 102C again, fan speed 1 engaged.. car reached 104C (on idle) and although fan was operating all this time at speed 1 the temperature according to the testbook wouldn't lower from 103-104 degrees..
So it's obvious that for some reason the heat from the radiator cannot be "removed"!!! since fan wasn't able to cool the coolant down..
Problem with radiator? problem with water pump? sth else??
My mechanic said that it doesn't seem like waterpump because even at higher revs it couldn't cool the system down, which should normally do and more likely seemed to have some kind of problem with radiator..
opinions?
 
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