Alfa Romeo Forums banner
1 - 3 of 3 Posts

·
Moderator
2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
Joined
·
17,737 Posts
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.
 

·
Moderator
2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
Joined
·
17,737 Posts
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.
 

·
Moderator
2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
Joined
·
17,737 Posts
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.
 
1 - 3 of 3 Posts
Top