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thread: Radiator Fans not working (Rev 2 Turbo)

  1. #1

    Jan 2014
    kent
    7

    Radiator Fans not working (Rev 2 Turbo)

    Hey guys, My Radiator fan (cooling fan No.1) is not getting any supply (12V from the car loom, female connector) when the water temp senor is disconnected and I cant seem to figure out why. I am getting supply (12V from the car loom, female connector)to the air con fan though (cooling fan NO. 2)

    Here is the situation:
    All fuses (front fuse box and 7.5A gauge) are all ok.

    Replaced all relays with known working ones.

    I am getting 12v at the relay on cooling fan No.1 when the water temp sensor is disconnected.

    there is continuity between the rad fan connector and rad fan relay.

    replaced A/C amp with a know working one and still nothing

    Anything else I have missed??

    Below is a wiring diagram

    Am I right in assuming that if the test on the harness that goes into the A/C amp checks out, then it safe to assume I do not have a wiring issue?

    Wirging Harness Test:
    https://scontent-a.xx.fbcdn.net/hpho...85467248_o.jpg

  2. #2

    Jan 2014
    kent
    7
    Can a Mod please move this to electrical please :D

  3. #3
    cdwood2010's Avatar
    Sep 2010
    Earls Barton
    6,003
    Only if you promise to stop posting the same thread multiple times.

    Chris.

  4. #4

    Jan 2014
    kent
    7
    Apologies, I wanted to delete this one as I noticed it was more suited to the electrical portion of the forum but couldn't find that feature

  5. #5
    AlunJ's Avatar
    May 2005
    Caerleon, South Wales
    749
    Why're you running it with the water temperature sensor disconnected, out of interest?

    It's a thermistor type sensor, with a high resistance (such as you'd get from disconnecting the sensor) indicating a low coolant system temperature. My guess is that the no3 cooling fan relay isn't being switched - which'd cut power to the no1 engine cooling fan and would leave the power to the no2 air con fan unaffected.
    It's a 2.0 inline four that thinks it's a viper v10. What's not to love?

  6. #6

    Jan 2014
    kent
    7
    Why're you running it with the water temperature sensor disconnected, out of interest?

    It's a thermistor type sensor, with a high resistance (such as you'd get from disconnecting the sensor) indicating a low coolant system temperature. My guess is that the no3 cooling fan relay isn't being switched - which'd cut power to the no1 engine cooling fan and would leave the power to the no2 air con fan unaffected.
    I disconnected it as this was a test in the BGB (see attached) which should make both fans power on, this test also works on my NA, (when unplugged, fan cranks to full RPM) which also has A/C

    I have replaced all the relays with known working ones (from the NA), Do you think its a wiring issue?

    Also id like to add that the previous owner has removed the A/C.

    http://www.electriciansforums.co.uk/...g-fan-test.jpg

  7. #7
    AlunJ's Avatar
    May 2005
    Caerleon, South Wales
    749
    Ahh, fair enough. Has been some time since I've been looking at the coolant system end of an mr2 :blabla: There's something staring me in the face on that original diagram that I missed yesterday that makes sense if the air-con hardware has been removed.

    Look for continuity between one of the pins of the no.1 cooling fan relay socket and pin 10 on the A/C amp. You should also have continuity from one of the pins on the no.2 cooling fan relay to the same A/C amp pin.
    Both those relays are switched by that amp pin, and there's normally an aircon pressure switch between the amp pin and the relays. If the connector for the aircon pressure switch is disconnected (and the connector not bridged) then that'd cause no.1 fan to fail whilst no.2 fan would still be functional.
    It's a 2.0 inline four that thinks it's a viper v10. What's not to love?

  8. #8

    Jan 2014
    kent
    7
    Ahh, fair enough. Has been some time since I've been looking at the coolant system end of an mr2 :blabla: There's something staring me in the face on that original diagram that I missed yesterday that makes sense if the air-con hardware has been removed.

    Look for continuity between one of the pins of the no.1 cooling fan relay socket and pin 10 on the A/C amp. You should also have continuity from one of the pins on the no.2 cooling fan relay to the same A/C amp pin.
    Both those relays are switched by that amp pin, and there's normally an aircon pressure switch between the amp pin and the relays. If the connector for the aircon pressure switch is disconnected (and the connector not bridged) then that'd cause no.1 fan to fail whilst no.2 fan would still be functional.

    Awesome reply, I have not looked at the A/C pressure switch to check to see if it is bridge, where is its location? also this may be a bit vague but is there any other scenarios you can think of in which would produce this type of error? (connector not getting a supply)

  9. #9

    Jan 2014
    kent
    7
    update: I think I found it on my NA, its located just behind the power steering reservoir with a 2 pin connector, that has one red and black wire, I going to see if I can find this connector on my turbo and see if the previous owner bridged the 2 wires :D

  10. #10

    Jan 2014
    kent
    7
    Hey guys upon testing, I noticed that from the car loom connector (female plug) on the A/C side I was getting power but when i tested the other terminal for continuity to ground, there was none, does this mean I may have a grounding issue, if so where are the grounds for the Rad fans?

    Here is the ground i am referring to:
    https://fbcdn-sphotos-f-a.akamaihd.n...74944630_n.jpg

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