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Cooling Fan Dropping Resistor Problem in 2010 Cruze 1.8LS

24K views 18 replies 10 participants last post by  Blasirl 
Hmmm a 2010 LS, must be outside of the USA.

Dropping resistors are used to reduce the speed of the blower motor, not the most efficient way, but sure the cheapest. !.4L uses two dropping resistor and three relays controlled by the ECU, only one relay is energized at a time.

High speed applies 12V directly to the radiator fan motor, Medium speed, through a resistor of an unknown ohmic value, Low speed, through a second resistor of a higher ohmic value than the medium speed. Each has it own fuses.

Guessing your LS is only a two speed, high and low. GM could be nice for a change and specify the resistance value in the circuit diagram, and practically all resistors have the resistance value stamped on the resistor. Gathering GM doesn't doesn't want to confuse their idiots with facts. You also have a fuse soldered in series with your resistor, it should be stamped with the voltage and resistor value. Can be checked for continuity with an ohmmeter for near zero ohms on the lowest range.

If a resistor overheats will be burnt, yours doesn't look that way. The reason why that fuse is soldered in, they want you to replace the entire module for more profit. How do I know this, talking to an retired engineer not keeping secrets anymore.

Typical operation is that a thermistor measures temperature, if exceeds a given point, the low speed is switched on first, if after a given time, this does not cool the coolant, than switches to high speed.

GM could also specify the current draw of the fan motor with 14.4 volts applied, typically in the 25-30 ampere range, this is the key test to tell if the motor is operating properly, again they omit this most important test. Could even specify the speed of the fan using a photo tachometer. Another valuable specification.

With this data, these simple very basic tests can identify a problem instantly, but the attorneys won't permit this, say would make them liable for a warranty replacement. So say test it against a known good unit, but how do you know its good without any specifications.
Can guarantee you, engineering provides all these specifications.

And I say to GM and others, shame on you.
 
167 bucks for the 1.4L radiator fan.



Good reason for testing it first, unless you have money to blow. Then what's wrong with it, a bearing that need lubrication, worn brush?

What about a dirty relay contact causing inoperation, was reason the reason my radio was flashing on and off, so should I have replaced the radio first? If I did, sure wouldn't cure the problem. Have to find the problem first.
 
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