Radiator Fans - Need help on the road!! | FerrariChat

Radiator Fans - Need help on the road!!

Discussion in '365 GT4 2+2/400/412' started by SouthJersey400i, Jul 2, 2010.

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  1. SouthJersey400i

    SouthJersey400i Formula 3

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    Romulus, NY (Finger Lakes)
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    Ken Battle
    I am in fix one break two mode!!

    I have now identified my AC issue (bad switch on the dryer).

    I am on a 4 day vacation trip to the Finger Lakes. The interstate came to a sudden one lane situation and stop and go, and my temperature went to 110+. I finally got off the road and was pushing some coolant out the overflow tank. I stopped for fuel and a little look around. I took an alternate route where I could set an easy pace. To shorten the story, I found that none of my fans were running. I have disconnected the AC compressor so that I can turn on the RH fan with the AC switch and not run the compressor. That gives me one out of three fans, but I am running 10 degrees higher than normal for easy driving.

    I am on the road and do not have (yet) a multi-meter to check fuses and power to fans. I will get equiped better in the morning and do some basic checks. I have spare fuses but it looks like the switch since two fans are out.

    Here are my questions:
    1. Where is the switch (or switches) that turns the fans on? I can find the relay but do not know where the switch is. Send a pic if you can!
    2. Does the same switch turn on both the center and left fan?
    3. If the AC is not on, does the right fan come on with the same switch?
    4. Or are there staggered switches to turn on fans?
    5. What temperature do the fans come on?

    It looks like the temperature indicator is the single wire sensor near the front of the "V", but a switch would normally need two wires.

    This forum is great. I am hoping for some answers when I log in tomorrow at breakfast. Thanks in advance!
    Ken
     
  2. Ak Jim

    Ak Jim F1 Veteran Owner Rossa Subscribed

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    North Pole AK
    I will start off by saying my car is an "older" 365 GT4 and while there are a lot of simularities there are also a lot of differences. One of the first things I did when I got my car is I purchased the wiring diagram from (I think) Paul Bennet. His diagram is a hugh improvement over the dinky diagram in the owners manual. He has color coded all of the wires and you can really zoom in to check out where all of the wires go, he has also labeled all of the componets. This makes it easy to trace the wires and circuits and figure out how things are supposed to work. In theroy then you can use logic to figure out how to trouble shoot any problems you might have.

    Now getting down to the radiator fans. On the 365 there are only 2 fans, a right and a left. The right fan comes on when ever the A/C is turned on reguardless of the engine temp. When the engine temp gets above a certain temp both fans run reguardless of the A/C. The 365 has two coolant temp sensors. One is for the radiator fans the other is for the gague. Both of these sensors complete to ground when they are activated, this is the reason there is only one wire. The sensor that operates the fans is a simple on off switch. As far as the location I can't help you with that.

    Looking at the wiring diagram in your situation (fan runs with A/C but not high temps) I would think the temp sensor is bad. This is because at least on the 365 one circuit supplies the low amperage positive to each of the relays. If this circuit was bad then you would not have any fans run. Since both of your temp operated fans don't work it would rule out a bad relay since each fan has its own relay and high power circuit. While both relays could fail it is unlikely they would both fail at the same time.

    To further trouble shoot your system you need to find the temp sensor that controls the fans and remove the wire and ground it. When i do this sort of work I use a jumper wire with aligator clips on both ends and a fuse holder with a 10 amp fuse in the middle. Anyway, I would bet that when you complete the ground on the wire to the temp sensor the two fans will turn on. If this is the case then the temp sensor is bad. It could be that the wire has simply come off of the terminal.

    I had one of the fresh air fans quit in my car. I took the front lower piece (the body work below the bumper) off to get to the fan. I used a jumper wire to power the fan and it ran fine. It turns out the wire came loose from the fan switch inside the car! All it took to fix it was take out the ashtray and hook the wire back up.

    Good luck with your problem. If gounding the wire turns on the fans you could always jerry rig up a way to turn them on and off manually, at least until you get home.
     
  3. SouthJersey400i

    SouthJersey400i Formula 3

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    Jim
    Thanks for input. My logic was same as yours and I went right for the temp. switch. I got the manual out last evening and found the switch is in the base of the radiator and turns on at 87 C (but this is cold side of radiator). The switch is a 2-wire switch with one side gong to ground. I got the wires out and just connected them together expecting the fans to spring to life. NO such luck. The fuses are both good as would be expected. The issue in this car is the relay panels are not well made. I found one of the coolng fan relays already rewired off the board and its wires are a bit 'toasty'. I swapped relay to the other fan with the horn relay which is the same type and this did not work.

    I have not yet found the common flaw. I am off to NAPA to get a multi-meter and some wire and connectors to find a way to 'hot wire' at least the LH fan which is easy to reach in the engine bay.

    I sure will look into getting one of those wiring diagrams!

    I'll give an update this evening. Driving home Monday may be a real "trip"!
    Ken
     
  4. open roads

    open roads F1 Rookie

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    Stan
    Good luck on the hotwire.

    In the old days, I had a Healy overheating and had to put the heater/aux. radiator on in the summer. It wasn't fun but it got me home.
     
  5. jacques

    jacques Formula Junior

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    Having owned my 1980 400i for 12 years, I have had to replace the radiator temp fan switch twice. NAPA caries the item for $20USD. It now comes with a 2-wire connector on it that is FAR superior to the naked spade connectors. They also have the the female counterpart available. Buy them, and eliminate the old female spade connectors . I found that the crud from the road is the likely villiain. These new connectors eliminate that. Also, do not make the mistake of puting ANY compound or teflon tape on the threads of the switch, as that will give the sensor an entirely false reading by aprrox, 15 degrees too late, to the brass sensor. I'm going to buy a dual fan harness($60USD) with the A/C switch feature and only use the stock relay on the board to trigger the new relays in the new harness.. or you can eliminate the stock wiring altogether, leaving the old wiring in place for posterity. I hope this is of some value to you. Thank you. Jacques.
     
    Last edited: Jul 3, 2010
  6. SouthJersey400i

    SouthJersey400i Formula 3

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    Jacques
    Your history and plans are good for me. I said to my wife last evenng, 'I wonder if just removing the switch connectors, cleaning them and reinstalling them did the trick.' I'll look into NAPA switch. I also considered wiring from scratch but I like your idea about adding a relay that works off the original relays for the control signal only. I think I can finda neat place forthe relay under the air inlet trunks over the front fenders.

    All will be clear when I get back to my shop! I'm hoping foranother good day and I'll even attempt a bit of AC today if all goes well. Temp heading to 90 today in the Finger Lakes and hotter tomorrow for the ride home.

    Thanks
    Ken
     
  7. SouthJersey400i

    SouthJersey400i Formula 3

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    We finished our 4 day trip to Finger Lakes and made the return trip in near 100 F heat. Fans ran without a miss. In some traffic lights I saw 110 C on the gauge but no steam out and cooled down once in motion again. Who knows why, but I will be digging into it. This problem is very similar to intermittent fuel pump failure that I overcame in 2009. Once again the fans like the pumps are high amp users and they overload the under-designed relay panel.

    Jacques, I am interested in the two fan relay. Is this a NAPA part? If so, part number? Thanks
    Ken
     
  8. jacques

    jacques Formula Junior

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    Ken and all..Google car fan wiring harness..you will find that all of the fan makers make them. Aslo.. you will find several theories and variations. Pick the one that you need. I personally think that ones with fuses and relays incorporated is the way to go. Why try to re-nvent the wheell..Allie Oop knocked the corners off that block centuries ago, Sixty bucks gets it done and your on the road in an hour or so. Keep us posted.Jacques.
     
    Last edited: Jul 6, 2010

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