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  1. #1
    Join Date
    Jun 2017
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    Unhappy Fans, over heating and other issues

    I am working on my daughters 99 LHS with multiple issues that may be connected and at a loss at trying to figure it out.


    Lost coolant, fixed and filled


    Heater is stuck on high through the dash, no control over settings. Swapped ATC head unit, the same. New motor resistor is coming today. She pulls the fuse when she doesn't need heat


    Radiator fans not working

    Replaced the coolant overflow tank and bleeding the system wasn't going well.
    I opened the bleeder and no air or antifreeze came out, so I ran the car to hopefully purge it. All was good at idle for 20 minutes until my daughter pulled the blower fuse (it was hot in the car) Within 5 minutes the temp shot into red. And I seen the fans weren't working
    This morning I siphoned antifreeze through the bleeder and it did suck down a good amount from the tank. So This could of been the issue with the over heating along with the fan but pulling the blower fuse is what sent the temp crazy. So the heater on high has kept the temp down I'm guessing, right?


    Now with the fans. So I noticed the fan relay was not seated so I pushed it down, could this have caused an issue? Being there is no way to tell how long the fans haven't worked I can't guess but swapping relays didn't make them work either. Where do I start looking before I put a toggle switch on it?


    She was having an overheating problem randomly the last 2 weeks and lost alot of coolant twice, cars still runs great though. Oh and the ground strap under the overflow tank was shredded so I replaced that.


    Being that coolant sprayed all over the pcm and fuse block, maybe somethings failing to control the ATC and fans? Is there a connection to any of these problems?
    Any help much appreciated

  2. #2
    Join Date
    Sep 2004
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    Old Hickory, TN
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    The fan set can fail and that appears to be your problem.

  3. #3
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    Jun 2017
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    Quote Originally Posted by done View Post
    The fan set can fail and that appears to be your problem.
    Fan set? Also relays are good, forgot to mention that

  4. #4
    Join Date
    Sep 2004
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    Old Hickory, TN
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  5. #5
    Join Date
    Mar 2012
    Location
    SW Michigan
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    The schematic I have is for a 2004 but it shows two relays for the fans a lo and high speed relay with a separate 40 amp fuse for the lo speed relay and the hi speed relay shares 40 amp fuse with AC cutout relay there is also a 10 amp fuse that powers the relays to close the contacts. I would check that 10 amp fuse then test the fans use a rechargeable battery from a drill next I'd check continuity of the wires from the fans to the relay board. You can also test the relays these are normally open relays so you should have infinite resistance between two of the pins and a resistance of some value between the other two. Last I'd check to see id you're getting the signal from the PCM to the relay board. Take the relay out and use a multimeter to the sockets that power the relay the 10 amp circuit. Run the engine until it reaches temperature to see if the pcm energizes the relay.
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