"308 Fan Logic ?"

Discussion in '308/328' started by edworak, Jun 18, 2007.

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  1. edworak

    edworak Karting
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    Jun 10, 2007
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    Ed Dworak
    I just replaced the radiator in my 1982 308. I trying to test the fans. If I turn the key on with the motor off and turn on the air conditioner the right fan turns on. If I start the car and let it warm up with the air off eventually the right fan turns on. When is the left fan (driver's side) supposed to turn on?
     
  2. miketuason

    miketuason F1 World Champ
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    Both fans should turn on when the coolant reach a certain temp. even if the AC is off
     
  3. Birdman

    Birdman F1 Veteran
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    Mike is correct. The AC turns on one fan, the thermostatic switch in the radiator turns on BOTH fans. Keep in mind that each fan has its own relay and fuse. So if one fan comes on with the thermostatic switch, the problem is not the switch. The problem is either the relay on the malfunctioning fan or the fuse, or perhaps the fuseblock itself. (They are known to melt on the fan circuit, which are the rightmost pair of fuses on the right fuseblock). Get out your multitester and start at the fuseblocks and work forward until you find the problem. The schematic and the list of relays are in the owner's manual. Of course you could also have a defective fan, but that is the least likely scenario.

    Birdman
     
  4. CCCVIII

    CCCVIII Karting

    Dec 7, 2006
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    The thermal switch ($29 Napa Auto Parts) is suspect.

    With the ignition key on, take a jumper wire and cross the thermo switch. If BOTH fans come on the thermo switch AND the fans are ok. If not, replace the thermoswitch with one from Napa Auto Parts. VW used the same switch, too

    If only one fan comes on, make a power lead wire from the BAT. Clamp it to something sharp and put it in along the power lead at the butt joint as close to the fan as you can to test the fan thats not working.

    If the fan powers up (key on), the $300 fan motor is good but there is a wiring issue up stream.

    Lets not go there until you check the fan motor with the power lead and the thermoswitch with a jumper.

    good luck
     
  5. edworak

    edworak Karting
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    By thermo switch, do you mean the one at the bottom of the radiator next to the return hose? The cooling system diagram in the Ferrari parts catalogue calls it "thermal contact, part # 101507." I don't know if I can get it out of the radiator without taking the radiator back out.
    As part of my troubleshooting I swapped the right and left fan relays. The right fan still works as it's supposed to but the left fan still doesn't work. I replaced both fuses for the fans, the last two on the right in the fuse bock, stiill no luck!
    I've owned the car 20 years next Thursday. I know because it was a 40th birthday present from my wife and I'll be 60 next Thursday. About 12 or 13 years ago I had fan motor problems and Steve Tillack's shop in Southern Cal replaced both fan motors with 328 fan motors. They were supposed to be an updated fan motor and in his words "bulletproof." I don't really suspect the fan motor itself. Later this afternoon I'll try jumping the switch at the bottom of the radiator if that's the one you guys are refering to. I live in northern Nevada and the nearest Ferrari repair shop is in Walnut Creek about 300 miles away so I pretty much do all of the work on it myself. It gets real frustrating when minor problems like this are so time consuming.
     
  6. BigTex

    BigTex Six Time F1 World Champ
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    That's the one....pull the wiring and jump it in the plug..

    Fan motors CAN fail as I've recently replaced on, it wasn't $300 only about $142 at the wholesale level.....

    Welcome .....hang in there, we'll help you!
     
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  8. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Two Time F1 World Champ
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    Yes you can, believe me. Don't even think about pulling that radiator out for that. A simple crescent wrench will work fine.

    Use the 180 degree aftermarket VW switch if it needs replacing.
     
  9. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Two Time F1 World Champ
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    When I first saw the heading on this thread I thought it was about why would someone be a fan of the 308.

    I was getting to settle in for a few minutes on the keyboard.
     
  10. Birdman

    Birdman F1 Veteran
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    If one of the fans comes on when the radiator gets to temp as he says, the thermal switch is NOT the issue.

    If it's not the fuses, it's wiring, a relay, or the fan itself. I am assuming you didn't just replace the fuses but actually check and see if there is voltage on both sides of the fuses using a voltmeter. The fuseblocks themselves are more likely to be the issue than the fuses.
     
  11. tvine

    tvine Formula Junior

    Jul 19, 2006
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    Tom Vine
    Back to your original question.

    If it's like a '79...right fan should run with AC on regardless of temp. Both fans should run when temp above switch setpoint, about 180*F regardless of AC on or off.
     
  12. edworak

    edworak Karting
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    The largest open end wrench I own is 24mm and it's too small so I tried my large crescent wrench. Actually, my adjustable wrenches are so old they say "Crescent Manufacturing Co." on them, however, it wasn't a problem to remove the thermal switch on the bottom of the radiator without removing it from the car except for having to drain the coolant again. I cleaned the thermal switch up on my wire wheel on my buffer and it is as clean as new. If you rotate it you can read "Veglia", "1N" , "85-76", and "73-0.2" on the sides. I drove down to the NAPA store 30 miles away and the guy was very helpfull but then he asked "Do you want the 160 or the 180 degree one?" I didn't know until I got home and read the posts. Tomorrow I'll drive back down to the NAPA store and get the 180 one. Also my DC meter isn't working so I'll pick a new one of those up at NAPA also. I started this marathon three weeks ago so what's another day delay? Everyone has been very helpful and I've learned a lot. I never knew about "Burping" the radiator and thought the expansion tank was supposed to be full, not full 'til approx. 3 inches from full. Also, I replaced my 1.1 bar radiator cap with a 0.9 bar cap as the owner's manual suggests. I'll keep you posted on my progression tomorrow. Thanks.
     
  13. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Two Time F1 World Champ
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    You may want to go back to the 1.1 bar. Don't throw it away.
     
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  15. BigTex

    BigTex Six Time F1 World Champ
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    No you went the wrong way... 1.1 Bar is correct, there was a Tech Bulletin after the Manual was printed.....:D

    Radiator bleed screw is absolutley required to avoid vapor lock at the rad.......often several attempts to burp it are required......


    I thought we ruled out the temp switch, if one fan works......

    Really not much difference, in 160 vs. 180 degree as the system reaches full operation anyway......
     
  16. BigTex

    BigTex Six Time F1 World Champ
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    Yea you want 3 - 4" above the fluid in the rear expansion tank.....
     
  17. BigTex

    BigTex Six Time F1 World Champ
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    Unplug the inoperable fan and hit it with 12v direct, let's see what we have there......

    It's the same fan as the 12 cylinder Jag XKE,I posted the part number or I can get it for ya.....
     
  18. CCCVIII

    CCCVIII Karting

    Dec 7, 2006
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    I just went through this on my 1979 308GTB.
    DO NOT PULL THE RADIATOR FOR THIS
    1. with the ignition ON
    2. jump the two wires at the bottom of the radiator (thermal contact, part # 101507) with a wire (or any metalic device).
    3. both fans come one.
    now, REPLACE thermal contact, part # 101507 with the cheap 180 degree VW "thermalswitch"
    tools - an Ace Hardware 10" cresent wrench opens wide enough. Large plyers will undo it too. Its not very tight.
    4. have the new "thermal switch" with pipe sealant on before you remove the orginal thermalswitch.

    procedure - Old switch out, new one may take 30 seconds even if you're in the middle of a conversations with the neighbors daughter, so to speak.

    5. the radiator expansion tank will drop about 2 qrts of water. Fill.
    6. run the engine and bleed the radiator and when the engine's hot. check the "burp" bolt on top of the engine thermostat.
    7. drive and heat the system up.
    8. when the engine is 190+/- stop turn the engine off. turn the key on and listen to two fans running. Make a visual check. Done!

    Do steps 1,2&3 before wasting time with relays and all the rest.
    And, the second time (if ever), you'll be an expert.
    good luck
     
  19. CCCVIII

    CCCVIII Karting

    Dec 7, 2006
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    additional thought re ruling out thermoswitch if one fan works

    right fan should work when the AC switch is turned on.
    BUT, that doesn't test the thermoswitch.

    That test of the thermoswitch requires "ignition on" AND jumping the two wires at the thermoswitch (jumper/hold together-whatever).
    if both fans come on. replace thermoswitch
    if right comes on, but not left when you jump the thermoswitch, that means the left fan may be bad. Test it.
    If the left fan doesn't run make a power wire from the battery and put something sharp (paper clip/ice pic in the butt joint under the left motor and touch the power wire.
    If fan runs - the problem is the wire between the two fans, but if it doesn't it means the fan motor is wornout.
     
  20. Birdman

    Birdman F1 Veteran
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    Gerald,
    No offense, but have you looked at the schematic? The fans are not wired together. Certainly testing the fan motor right to the battery is a good test of the fan motor though.

    Each fan has its own fuse, and relay(s). The fan that is on the AC circuit has two relays: one to turn it on when the AC is on, and one for the thermoswitch. That means that if one fan is not working, it can be the motor or the wiring as you stated, or it could be a fuse, the fuseblock is melted or the contacts dirty, the relay is bad, the contacts on the relay are dirty and so on.

    The poster (Ed) has stated in his first post "If I start the car and let it warm up with the air off eventually the right fan turns on. "

    This means the switch in the radiator is fine. Moving on....

    If it were me, I would connect the two wires from the thermoswitch together so that fans will come on with the key on and the engine cold. Then turn on the key (no need to start the engine), start at the fuseblock with a multitester and simply follow the circuit until you find the issue. I say start at the fuseblock because it is 10 times more likely that the issue is at the fuseblock or relay than at the other end.

    Birdman
     
  21. maurice70

    maurice70 F1 Rookie

    Jan 25, 2004
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    I rewired my fans up on the GT4 so that when the A/C is on both fans run.I like to keep condensing temps down.The rad temp switch still works and brings both fans on as well
     
  22. edworak

    edworak Karting
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    First of all, yesterday, I pulled the two wires off the thermo switch and was going to jump them with an alligator clip jumper. I accidently touched the two wires together and both fans came on so my problem was not the fan motor. Yesterday afternoon I drove down to the NAPA store armed with the VW thermo switch # and the Sorenson part # I found on this website. The NAPA store ran the numbers in their computer and said their part # was FS163 but they didn't have it in stock and it would take about 7 to 10 days to get one. The guy at the counter suggested I try the VW repair place across town. I drove over there and suprisingly they have a great supply of VW parts even though they are an independent VW repair shop. The guy looked up the part # I gave him and he asked the same question. Do I want the 180 or 160 switch? I told him the 180 and he went and checked and didn't have it in stock but said he could get one by this morning. I noticed he carried Bosch relays so I also went back this morning with the two most common relay numbers on my 308. He had both of those in stock along with my ordered thermo switch. The thermo switch cost $10.99 plus tax! I drove home and replaced the switch, added the coolant back in along with another gallon of anti-freeze for the gallon I spilled on the floor. I started the car and let it warm up and vola both fans came on! I don't know why one fan wouldn't work with the old switch. All I know is by replacing the switch, now, both fans work.
    The owner's manual states use a 0.9 bar radiator cap. Since a bar is 14.5 psi that makes it a 13 psi cap. I'll keep the 1.1 bar (16 psi) cap in case I have problems with the lower pressure one.
    Thank you for all of your help and suggestions!
     
  23. CCCVIII

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    The new thermoswitch lasted less than 500 miles. Its out again. This time I intend to replace it with a 180 VW thermoswitch.

    All other systems work normally including both fans. Before switch failed, engine maintained 180+/- degrees running at speed and will come up to 195/200 on winding roads using alot of 2nd & 3rd gear cornering revs.


    Got this replacement from well known independent Ferarri shop but don't know the manufacturer. Will now replace with a VW thermoswitch to determine if quality control of switch improves.

    And, I did study the wiring diagram with the help of Hubble telescope for magnification. Of course, the thermoswitch triggers the relay which then completes the 12V circuit to the two fan motors. In this case, the fuses are good. A visual inspection of the back of the fuse block reveals noting unusual. That's a switch, so to speak.
     
  24. Birdman

    Birdman F1 Veteran
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    Are you sure the switch is toast and it's not just old crappy connectors on the wiring harness? Mine were quite oxidized and didn't always make a good connection.

    Birdman
     

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