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Thread: AutoCool in Smyrna?

  1. #21
    Senior Member DL4567's Avatar
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    I thought I had a photo handy of my relay compartment for these needs of easy reference, but can't find it now (of course). But I'm 99.9% certain I don't have original relays of any kind, like the (notorious) blue one.

    Well, this sounds like a problem that certainly needs to be addressed. The guy at the AC shop also said he was concerned about high pressure in the system sending me on my way with only one fan.

    So, what are the steps to troubleshoot? Can I swap the cooling fan relay out with another to confirm or rule that out? What's next after that? Check if the connector at the fan is getting voltage with a multimeter?
    Derek L
    VIN 5302

  2. #22
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by DL4567 View Post
    I thought I had a photo handy of my relay compartment for these needs of easy reference, but can't find it now (of course). But I'm 99.9% certain I don't have original relays of any kind, like the (notorious) blue one.

    Well, this sounds like a problem that certainly needs to be addressed. The guy at the AC shop also said he was concerned about high pressure in the system sending me on my way with only one fan.

    So, what are the steps to troubleshoot? Can I swap the cooling fan relay out with another to confirm or rule that out? What's next after that? Check if the connector at the fan is getting voltage with a multimeter?
    You probably have fused jumpers in the blue relay socket. Just use a multimeter to verify you have voltage on all three terminals. If so, get under the car and meter the connector for the fan relay not working.

    Your AC guy is correct, AC high side pressure will run higher with only one fan working.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #23
    Senior Member DL4567's Avatar
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    I haven't had a chance to do any electrical testing yet, but I found the photo I took of my relay compartment. Looks like the fan-fail socket is no longer there, but the fan relay is one of the Bosch silver ones (the one in the bottom-left corner of the photo, correct?). Whether the cause of my one fan running is the relay or not, Dave M, I'd like to replace it with one of your fan relays. I saw in the other thread recently where you mentioned it keeps the fans running for AC cycles less than 20 seconds -- that sounds great. I hate the fans turning on and off so often, combined with the clicking like a bunch of people. I'm guessing since the fan-fail socket isn't even there, there's no point in getting one of your fan-fail relays as well?

    Oh, also, isn't this when my fan-fail light should be on? I know the bulb works -- it's an LED. It really bugs me how long only one fan has been running. It could be years!! Wonder if the increased pressure has anything to do with my AC struggling to hold freon the last few years.







    Derek L
    VIN 5302

  4. #24
    Senior Member Bitsyncmaster's Avatar
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    Your fan fail socket has been removed and the fused jumpers have been hard wired in it's place. Without a working fan fail unit your fan fail light will not indicate when you have a fan failure.

    It is normal that the relay beside that missing fan fail socket is the fan relay. You could pull it and test your fan does not turn on. But you need to find the cause of only one fan running first. It could be just a bad fan motor or could be a bad connection. Those two fuses on the jumpers are for the cooling fans.

    If you lift up that front relay bank, take a photo of the wires going into the relay sockets and I can verify if my fan relay will work. The fan relay needs to be wired like stock wiring.

    I see one of your relays (one headlight relay) has been replaced.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  5. #25
    Senior Member DL4567's Avatar
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    I got under the car today and checked the wiring at the fans. The source wires on the driver's side shows 11.3 volts, and passenger side (the one not working) was 10.1 volts. Then I tested the fans -- I used a battery charger for a quick power source, and jumper-wired both fans at the 12v and 6v settings. Both worked perfectly, with 12v and even at 6v (more on that below).

    I figured it was just dirty connectors, so I cleaned them as best as I could with sandpaper, and plugged them back in. Flipped the switch, and..... NOTHING!!!! Now neither fan came on. I wiggled the connectors and the driver's side worked again, but no amount of wiggling could make the passenger side come on.

    Unplugged it again, tested the passenger fan with the battery charger (still works). Tested the source wire again, it fluctuated around 6-7 volts. I know from testing the fan with a 6v source that it is enough power to make the fan come on, so I'm still stumped why the car wiring doesn't make it come on. Even when unplugging the driver's side, the passenger one still won't come on.

    I realize the car wiring is a bit more complex than just power to both fans yes/no, so what's going on? If there's something wrong with the relay, could that affect just one fan? Wouldn't both fans not work if the relay was defective? BTW, I checked all the fuses, they they all looked ok.

    Thanks for the help guys, it is much appreciated.


    Answers to other questions:
    Not sure how to lift the relay bank for a photo of the underside? It seems pretty firmly in place. Also, yep, my low beam headlight relay is a local auto store replacement, as the Bosch one suddenly quit working one night a couple years ago.
    Last edited by DL4567; 04-30-2016 at 05:14 PM.
    Derek L
    VIN 5302

  6. #26
    Senior Member Bitsyncmaster's Avatar
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    Stock wiring uses one fan relay to power both fans. In stock form, the output power of the fan relay drives the circuit breaker then the other side of the breaker powers the fan fail socket pin. From that fan fail input power pin you should have two jumpers, each jumper drives one fan.

    You lift the relay bank by removing a screw on two of the relay sockets. Then the row of socket should just lift up.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  7. #27
    Senior Member DL4567's Avatar
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    Thanks for the quick replies Dave! I'll get that photo of under the relays for you.

    This is what's frustrating me.... This doesn't make any sense! Can someone tell me why when there's voltage at the source connector, the fan doesn't come on when you plug it in??!?!?!?!?!!

    There's nothing wrong with the fan -- Again, when I just barely touch 2 wires from a battery charger putting out 6.75v to the (white) fan connector pins, it comes right on. 9.06 v coming from the source wires, I cleaned all the connectors as best I could, and still nothing.

    What am I missing here?!?!!?






    Derek L
    VIN 5302

  8. #28
    Senior Member Bitsyncmaster's Avatar
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    You can't trouble shoot voltage drops unless the load (the fan) is still connected. My be is when the fan is connected you will get zero volts. You may be able to stick your probes into the mated connector but if not, I use a very fine wire or a pin to puncture the insulation on the wire.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  9. #29
    Senior Member DL4567's Avatar
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    My VIN:    5302

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    OK, I'll try checking it when connected somehow.

    Here are 2 photos (flash/no flash) of the underside of the fan relay sockets. The far left black socket is the normal "fan relay."

    The 3rd and 4th photos (no relation to the issue at hand) are a mystery relay socket tucked away at the back of the relay compartment. Any idea what it used to be?







    Derek L
    VIN 5302

  10. #30
    Senior Member Bitsyncmaster's Avatar
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    Your Fan relay socket looks good. The center pin ground wire has been cut off but that ground is not required (It grounds the fans when turned off).

    That white floating relay socket at the back of the relay compartment is the HOT START relay socket. In stock form, it is not used. I sell a "hot start" relay which I use to eliminate the thermal time switch. It also can help if you have hot start issues.
    Dave M vin 03572
    http://dm-eng.weebly.com/

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