Question about 1998 Cadillac DeVille

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1998 cadillac deville coolant fan does not come on at 224 f, a/c fixed and fan will come on, the one on the left as you are looking at the car. but not the smaller fan now i had the smaller fan on the right as you are looking at the car hot wired in but it blew the fuse every time the a/c was turned on changed all three relays, temostat checked temp sensor. is it a way to isolate that fan on a switch or something that would allow it to work in conjuction with the a/c.

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  • nexus10110 Jun 02, 2010

    more info than i have gotten in all forums it's been 8 months with this problem thanks

  • nexus10110 Jun 02, 2010

    problem all the wires are gray seems like a fix to the fan motors but thanks any way

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  • Master
  • 6,784 Answers

HI. I have a very thorough, step by step procedure that will help troubleshoot this issue. follow carefully to isolate the problem, Use extreme caution when preforming this inspection procedure.


1
Check for broken wires or loose connectors around the affected fan circuit. Inspect connectors at the fan motor, relay, sensor or heat sensitive switch, and the Electronic Control Module (ECM)--your car’s computer control system. Also, make sure to check for a possible blown fan fuse. These are common and overlooked troublesome spots that may cause a fan to fail.

2
Run and bring the engine to warm temperature. With the engine running, use a voltage test light to check for power to the motor fan. Be extra careful and make sure to keep your hands and tools away from the belt, fan or any other engine moving parts. If voltage is reaching the fan motor, the test light should glow.

3
Turn off the engine after you see the light glow. Apply direct voltage to the fan motor from your car battery using a pair of spare wires. If the fan fails to operate, replace the fan motor. If the motor operates, your problem is in the motor connector.

4
Locate the heat-sensitive switch or heating sensor if the fan motor operates with direct voltage and the test light did not glow. You should find the sensor in the radiator, engine block, or thermostat housing.

5
Measure the resistance across the heating sensor with the multimeter. With the engine at cool temperature (engine off), it should register infinite resistance; with the engine at warm temperature (engine off), you should read low resistance. If both readings state infinite resistance install a new heating sensor, that’s the cause of your failing fan.

6
Check the action of the fan relay if the heating sensor is registering variable resistance. Your service manual should specify the power and ground wires according to color codes and the proper way to test it. If the fan relay fails the test replace it with a new one.

7
Check the connections going to the ECM after you determine the fan relay is working properly. If you find broken wires or loose connectors, make the necessary repairs. If you suspect a defective ECM take your vehicle to a service shop for a computer analysis. In most cases, the ECM is rare to be the cause of a failing fan. The above steps should take you to the root cause of your problem and help you fix the cooler fan.

Posted on Jun 02, 2010

  • nexus10110 Jun 02, 2010

    wich relay controls that fan i've been sent wiring diagrams a plenty but they are too small or distorted to view relay 1 2 3 if it a problem in wiring i would like to start at the right connector end pull pin for pin if neccesary

  • Michael Masters
    Michael Masters Jun 02, 2010

    Click here to view a more clear diagram of the relay location.

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