my 91 manual w/ ac sentra has a radiator fan that won't work. Switched the entire dual fan assembly, still won't work. Is there a fuse or relay I should replace??????? Procedure to follow????? Thanks all, Jeff

yes there are is fan realy(s) in the box under the hood. this is your diagnostic point for the circuit and it really helps to have a wiring diagram to do it. but basically if it is a 4 pin relay terminal 1 and 3 are power and 2 and 5 are grounds. do not use a test light to perform any tests. reason is you could fry a driver in the ecm if you jump one of the terminals with a test light. use a volt meter terminals 1 and 3 should have power with the key on. terminal 5 is the line that feeds the fans power. if you have a paper clip handy jump terminal 3 to 5 . make sure you figure out which terminal is what before you jump anything cause again jumping into terminal 2 will fry the driver in the ecm. the way to identify the terminals is if you look inside the terminal area of the relay the number is embossed in the plastic next to its terminal use a flash light to look in there. now match the terminals to where they are in the relay socket. when you jump terminals 3 and 5 in the socket the fans should turn on. providing you had power to terminal 3 during your voltage test. if you didnt have voltage you need to check the fuses. and that applies to either 1 or 3 terminals. now if the fans dont turn on you have a problem in the circuit from the relay to the fans. by doing your testing this way you are breaking the fan circuits into 4 smaller circuit helping you isolate the circuit thats causeing the problem. if the fan works you now know that 2 portions of the circuit are ok. these are the power supply ciruits for the fans the other 2 are the control circuits. if you had power at terminal 1 you know that circuit is ok. so that leaves you with the ecm part of the circuit this does not neccesarily indicate there is a problem with this wire from the ecm but that maybe the ecm is not grounding the relay because it does not see the request to turn the fans on. when you turn the ac on the fans should come on. keep in mind though the relay could be the problem if there is an adjacent relay that is the same color and the same amount of terminals you know works swap it into the fan relay socket and see if the fans work.( Hint: do that first) if you dont come up with something during these tests post it.