Cooling fans in Chrysler 300m

Could be anything from the temp. sensor to the computer to the wiring.

change the other one and see what happens

Replacing parts without testing them first runs the customer into a lot of money and frustration, not to mention making the mechanic look bad. Test all of the wires and relays and you'll find what needs to be replaced the first time instead of just throwing parts at it until you happen to replace the right thing.

check switch that goes to the fans,start at plug in at fans and go back until you see it,test with tst light,also crank it turn on ac ,on max they should come on.is on different circut,then you will know the auto fan switch is bad,also check to see if their is a fuse for them.sometimes thes fans loose connection on the inside of fan motor,use a hammer hit them with handle and they will start working again.

check connector plug from body to fans, the one you disconnect to take fans/shroud off. it might be plugged in but not making contact inside terminals.use some dielectric grease and I even use plastic zip ties to pull connectors tight. start engine and turn on a/c. both fans should come on at same time.