Cooling fans on 2001 chevy malibu will not come on unless ac on

replace the temp sensor its gone out of range
service the fans
these fans have carbon brushes maybe one is a bit worn set or something.!!!

Bad coolant temp sensor is my main opinion

Sounds like you have a problem with the coolant temp sensor or it related wiring.

You did not change the coolant temp sw. you change the ETC which sends a signal to the cpu. It looks just like the temp sw. Look on the driver side head and I believe you will see another one there or look the engine over for another sw just like the one you changed. Not sure what size engine you are asking about.

turn ac off then the fan will go off make sure ac button if you have one isnt pushed inwait a minute fan should turn off does temp gauge inside car raise in temp after running a while

there is a fan relay, and an AC relay that both turn the fan on at certain times, including when the AC is on. a coolant temp sensor tells the computer (ECM) to turn on the fan but only when the engine reaches a certain temp. an electronic component locator can show you where these sensors and relays are located. they are not very expensive. your local auto parts store can look that up for you.

replace coolant sensor connector?if so can u get a thermo lazer gun to check the block temp? this will tell u if the gauge is incorect,,,go ahead a bleed all the air out of cooling system and see if that does the trick

either the temp sensor is bad but, it sounds like the fan relay is stuck.
replace the relay its in the fuse box.

replace thermostat, this fixed my car, cooling fans keep coolant below temp guage parameters.

your coolant temp sensor on the engine block is probably faulty, however, keep in mind that if it really isn't all that hot outside they may not need to turn on. Once you activate the A/C the fans come on automatically since they have to cool the condensor...

If your car is not overheating do not worry about it.