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Discussion Starter · #1 ·
So here is how it goes, I go up to start the car doing a checkup make sure everything is fine etc...

I wait until the car gets to temp 175°F degree then the fans start kicking in... Alright I say to myself.

Then, I see the little bastards just simply turn off for a moment then they turn for another moment, then, they shut off and so goes on...

I must ask to myself.

Im not crazy right? This is not normal.
 

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Discussion Starter · #3 ·
There might be a short circuit going on, or the makings of what will become a short circuit.

Is this a GTV6? Original cooling fans?

It is a GTV6 and it has the original cooling fans too, plus I had replaced the Temperature switch sensor not long ago.

I agree I don't know what else could it be if something hasn't shorted, everything else seems to function properly.
 

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Alfa Radiator Fans

So here is how it goes, I go up to start the car doing a checkup make sure everything is fine etc...

I wait until the car gets to temp 175°F degree then the fans start kicking in... Alright I say to myself.

Then, I see the little bastards just simply turn off for a moment then they turn for another moment, then, they shut off and so goes on...

I must ask to myself.

Im not crazy right? This is not normal.
Check the fan sender unit switch and relay. I had an issue with one of the two fans in my 1990 Spider too...cleaned the electrical and replaced the unit and relay and both fans work fine.
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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The fans in our Alfas, the Milano, the 91 164S, and the 94LS do cycle on and off when the engine is hot and idling. It is expected, as the system temperatures rise and fall, depending on whether or not the fan is pulling air through the radiator, and the coolant temperature sensor senses this change in temperature, turning the fan on and off.

This is if the engine is just idling, car not moving, nothing steady state about that until the car is cruising at some normal relatively constant speed, and then there is enough cooling without the fan coming on, so the temperature becomes pretty steady state in nature, ie, no fan cycling needed. Indeed, usually no fan at all.

Seems normal to me, although evidently the GTV6 system is maybe less adequate, less cooling capacity, and so cycles more often at idle, or stop and go driving. Or, if the system has a flow problem (like many of us older types, lol), then the system would also cycle more often to compensate for the flow problem, to try to keep the coolant temperature within design bounds.
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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You could approximate it by using an infrared temperature gun on the thermostat housing to see what the different temperatures are, when the fan comes on and goes off.
 

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That behavior you are describing is not normal. The fans should cycle, yes, but they should run for quite a bit before shutting off. If they're rapidly cycling something isn't right.

I would suspect the switch or relay. You can try jumpering the two wires at the switch: if the fans run continuously in that case then the switch may be bad. If they show the weird cycling behavior then the relay may be bad, which you can test by jumpering the relay.
 
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I agree with @Gubi. The fans should turn off when the thermo-switch reaches the shut off temperature (I think it's 83C stock). If they cycle very quickly, I think thermo-switch might be bad, or you may have a bad relay. I'd check both.
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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What is the actual switching rate you mention? You haven't mentioned that yet.

The switch sensor could be more sensitive, narrower temperature gap hysteresis, causing the system to cycle more often instead of a switch with a wide hysteresis causing a wider gap between the actuation temperatures.

(We have that in one of our greenhouse fans temperature switches, where one waits for a long time, ie, wider temperature gap, between turning the fan on and off, and the other changes more often).

Otherwise, I agree, might also be just a bad connection, which stops conducting if it heats up, then conducting again when the power has shut off, ie, the connection cooling down below a certain temperature.
 

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With airflow on the radiator, the coolant should be maintained close to 85 by thermostat alone. Without airflow the fan switch cycles between 90 and 95. This is how all my cars (should) behave, Alfas etc. EG our 156 cycles between 90-95 every one or two minutes, so the fan could be on anywhere from 30 seconds to a minute. Diesels seem to take much much longer. YMMV etc.
 
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