How a cooling fan should work

Radiator fans come on only when engine reaches certain temperature or AC is switched on.

Cooling fan doesn't work - YouTube

? 7:16
www.youtube.com/watch?v=CPwzmyraGtg

Jul 19, 2009 - Uploaded by realfixesrealfast
This cooling fan use's a "cooling fan dropping resistor" to achieve low speed. It's pretty easy to ...

[Help] Radiator fan no longer works? - Automotive ' DSLReports Forums

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DSLReports
Nov 9, 2007 - 30 posts - ‎5 authors
Forum discussion: I have a Chevrolet Cavalier 2001 Base Model car. ... he thinks something else may be wrong with it still, since the fan doesn't turn on. .... ok you confused me... all I know is my temperature gauge is working.

The cooling fans are supposed to run any time the a/c is on in order to keep air flowing across the condenser. Your a/c will not work properly at idle if they quit.

Is your ac fan coming on when you turn on the ac? If it only getting hot when you turn ac on I'd say your ac fan isnt coming on so check your ac relay and ac fuses. Is your ac blowing cold

Water pump? Did you jump fan cooling switch (on thermostat housing) to see if fans come on?

CHECK TO SEE IF COOLING FAN IS RUNNING.IF NO CHECK COOLING FAN FUSE AND RELAY.THE COOLING FAN NEED TO BE RUNNING WHEN AC ON BECAUSE AIR CONDITIONER PUT A LOAD ON ENGINE.COOLING FAN KEEP RADIATOR AND AC CONDENSOR COOL.FAN NEED TO RUNNING.

Turn vehicle off. Allow to cool. Raise hood.
Try to see if the fans spin freely by hand. If not, replace. If they do spin, proceed to next step.
Next step-
Check coolant level, add if needed. Remember-radiator must be cool before opening cap. Make sure radiator cap is secure and tight if coolant was added.
Start vehicle. Observe coolant gauge as vehicle warms. Fans should come on when temp gauge reads halfway between c and h.
If fans do not come on see if they come on when you turn on ac or heat. If doing this makes them come on, suspect faulty cooling fan sensor switch. If they don't come on replace cooling fan sensor switch and fan relay.

that has 2 sensors one ac and one cooling should b a sensor on shroud near cooling fan

You evidently have a problemwith your engine cooling system. Check to make sure that the cooling fins on your A/C Condensor and Radiator are not clogged up with dirt and debris. Check that your mechanical fan clutch has some resistance to pushing it by hand. If it spins too freely. the fan clutch could be worn out. Check to see how much air it is actually moving through the radiator. When the engine is at operating temperature and the A/C is on, This fan should be turning at a very high speed and blowing HOT wind in your engine compartment. I believe that your vehicle is also equipped with an electric cooling fan. The electric cooling fan should be running any time the A/C compressor is engaged. If not, then you must diagnose this failure.

the sending unit has went bad. it comes on with the ac because it designed to overide the high temp sending unit or switch. should cause less then 50 bucks to get it replaced and only a few bucks if you do it yourself