Radiator fans inop.

If they BOTH don't work, I suspect just the thermostatic switch in the radiator. Pull the two wires from the switch, short them together and see if the fans come on. Each fan is run from a seperate relay that is powered from seperate fuses. It's possible that both fuses have crappy connections (fuseboxes in 308s totally blow and are the cause of 90% of the electrical problems) but to have BOTH not working is a coincidence. In the 1977, the far rightmost two fuses in the right side fusebox run the fans. Try cleaning the contacts and making sure of course that the fuses aren't blown.

The other 2 things that would cause BOTH fans not to work would be that the relays are not getting power to the coils (which comes from a fuse on the far left end of the left fuse box on a 77!) Check that fuse. Finally, the switch on the radiator connects the coil of the relays to ground, so be sure that one of the wires attached to the radiator switch actually reads close to 0 ohms to ground.

 

Bill,
If the fusebox is like the one on the 1977 308 (probably is) then the rightmost 3 fuses on the right side box are fed by one wire that comes into the top of the set, and the power is distributed to the three fuses by means of a "bus bar" that is riveted to the back of the fuse box. These rivets are the only electrical connection to the fuses and are notorious for becoming open circuits when they get old and get corroded. (They are also notorious for developing high resistance, getting really hot and melting the fusebox!) Check with a multitester that all three fuses are getting 12 V. This would explain a total lack of power to BOTH fans. (It was the cause of a lack of power to one fan on my car, but the other rivet was still working...) If they are not all getting power, solder a heavy wire across the top of all three so that they get power from the one spade connector that actually is connected to the big red wire bringing 12 V to that set of fuses.

Jonathan

 

Hi There,

I wrote a bit about it on Robert's website:

http://www.r-design.net/308/index_e.html

Just click on "TechTips."

Here is some of the text below to get you started, good luck!

Carl.



For this next check, I suggest you remove the fuse for the fuel pump. It will stop your carburettors being primed with fuel unnecessarily. With the motor not running and cold, but with the ignition in the "run" position, switch on the air conditioning. The right hand electric fan should come on. Now remove the two wires that fit on to the temperature sender at the base of the radiator. (figure 37) With the air conditioning still on, short out these two wires. The left hand fan should run. Now switch off the air conditioning but keep the two wires shorted. Both fans should still be running. If not, this is why your car will run hot when at a standstill. If the fans worked when the wiring was shorted but don't come on when the car is hot, then suspect the sender in the radiator. Remove it and check the continuity when the unit is placed in boiling water. It should close circuit at 84 degrees c. and open at 75 degrees c. If the sender is OK it may just be a case of having a dirty connection.

A word of caution. If your car has been involved in a collision at the front, chances are the wiring has been damaged and not repaired properly. The loom is quite vulnerable as it runs very close to the front chassis and an impact here will damage the wiring. Make sure the wiring is in good condition in this area. I have heard of cars that have been repaired and the fans wired up in reverse polarity, blowing air forward! Please check yours!

You could also try running the wiring directly from the battery. Should the fans run we need to delve into the fuse box and associated wiring. If they don't operate, it must be the motors (see below). Check for continuity between the fuse box, relays and the fans. If the wiring is good, check the relays. You should be able to hear them tripping when either the air conditioning is on, or when the temperature sender wiring is shorted. If not, try swapping the relays from the headlights (they are the same).

Check that the fan motors are operational. If there is voltage at the motor end but they are not running, then they are faulty. The fans may require a rebuild. The fans are made by Lucas and are not very well put together. It's a good idea to remove the fan motors to inspect them. The casing has a seam at its base which does not seal properly. This allows water to enter the motor assembly. A small amount of silicone sealant will cure this. Water can also enter through the bolts that hold the case on so make sure these have a watertight seal. If you take the casing off, make sure the brushes are in good condition and there is no corrosion inside. Grease the bearing at the opposite end to the fans and replace the case, being careful not to allow the armature to bang against the case due to the magnet. When replacing the casing, slacken off the bearing lock nut. (Note, as the motor is English, this nut is not metric, it¹s 7/16" ). After the casing is replaced, rotate the fan whilst tightening the bearing adjusting screw. When the bearing begins to bind, just back it off about 1/4 turn until it is free then lock the adjusting screw with the nut. To even out the wear, the fan motors can be transposed left to right. This is because the right side always does more work as it always comes on with the air conditioning. These motors were fitted to many English cars in the 1970's so if yours are beyond repair, try a Rover or Jaguar specialist. I am sure there would be plenty of these in the wreckers yards!

If all is well with the circuit and the motors are OK, but the fans still will not run we need to check the fuse box. This area is the most common source of electrical problems in 308's. Unscrew the two screws that hold in the fuse box that applies to the fans. (The location will be in your owners manual). With a multimeter check the resistance across the fuse block. It must have no resistance. If it does, here is your problem. These fuse boxes have a design fault. The upper and lower contacts are riveted on. They should be soldered. This means that after the brass fuse strips have oxidised over time the resistance increases. The fuse strip now acts like a small bar radiator, melting the plastic base or worse, catching fire. Sometimes, the fuse strip when it begins to warm, will distort and go completely open circuit without warning. This is most exciting if it is the headlight circuit! You may wish to check all the connections on the fuse box. For a permanent fix, remove the fuse box and clean all the rivets on the fuse contacts. Make sure you check the back of the fuse box as well. Solder every rivet to the strip. Now your fuse box is fixed for life! If it is beyond repair, the genuine Ferrari fuse boxes are very expensive. Expect to pay about $200 per side for a new one. If you don¹t care for originality, Hella make an excellent marine grade fuse box. I have never tried it, but it should work very well in a car.

One final note on the fans. Their efficiency can be dramatically improved by mounting them as close as possible to the radiator. The clamps that hold the fans are adjustable so move the assembly as close to the radiator as possible. I have mine only 3mm. from the radiator and have had no problems. I was careful to replace the flexible rubber grommets on the motor mount though, just in case. If you wish to mount your fans this close to the radiator, I suggest you do change these mounts. They are available from most stores that sell electrical wiring accessories for motor vehicles.

 

Check to make sure that power is flowing on either side of the fuses that power the fans. I had the same problem a few months back and it was a bad fuse block. On the front everything looked ok but the fuse jumpers came loose on the back and kept the fuses from getting power.

If you need a new fuse panel, check the archives as I posted a $40 repair that is much better than the Ferrari OEM that costs hundreds.

 

the fans have constant power going to them and the thermo switch engages to connect the ground.

9/10 of the time the ground wire has gotten corroded- to check this out simply remove the "hot wire" and touch it to a grounded part--fans should opperate. Also check with voltmeter to see if one of the wires at thermo switch is "hot". If not --look at fuses and other connections.

It is simply a process of elimination--

 

My '76 308 was running hot until I I had the radiator overhauled at a local radiator shop for $59.

Removing the radiator started a restoration of the whole front end of the car which included disassembling the fans, painting them, and reassembly. They are made by Lucas and are skittish. Took several tweekings of the shaft adjustment screws to get them running properly.

A 308 with a good radiator and properly managed coolant system should never overheat even in the worst traffic conditions on the hottest days. Warm, but never hot.

Everything posted here by others is correct: The fans have a constant +12v a on one lead and are operated by grounding of the other lead either by the thermostatic switch or operation of the air conditioner.

To test if the fan itself is working, using a volt meter, determine which lead has the +12v then ground the other, the fan should operate.

If you remove them, make sure that after you reinstall them you can feel a blast of air behind the radiator when they are on. If not, the wires have been reversed.

 

This is not technically true....the RELAYS for the fans have constant power and the switch on the radiator grounds them to close the relays and then send power to the fans. The fans never have power if the relays are not closed.

Birdman

 

Birdman is correct, and I stand corrected.

I was just recalling when I was "bench" testing the fans, which should only be done if the fans are held firmly in place by a wood vice or similar method.

Caution: If not held down when 12v is applied, the fans will become airborne and wreak all sorts of havoc on objects on the bench top, in the garage and even whack the Ferrari if its in the vicinity.

 

As a small aside, Tremclad Hammer Finish spray paint in Grey is a perfect match to the OEM finish of the fan motors. I painted mine and then sealed the join between the case and fan cover with household varnish applied with a brush. This PERFECTLY replicates the slop that came from the factory. Just a concours tip for the insane.

 

Hi Donald,
Are you kidding me? The fans FLY? That's a good thing to know. Man, I would hate to have a fan lift off and then land on my hood!!

Birdman

 

Just as a tip, build the fuse blocks first and then transfer them over to the car. Once the fuse blocks are built, the transfer should not take more than 10 minutes.

 

Do you have a link to this NAPA fusebox thread? I can't seem to find it.

 

!~@@!##$#$%$% bump.

 

Since Michael bumped this thread anyway, I thought I would mention that I have since made replacement fuseboxes for my 308 based on Nuvolari's design, with a little finessing, and I now have a template to build them easily. If anyone wants a set, I have built them for several other Fchatters now and they have been happy. PM me if you would like me to build you a set. (I have to build them to order because the bus bar arrangment is different depending on which model 308 you have).

Birdman

 

Birdman when I redid mine I used solid copper wire (piece of #12 wire) as a buss bar. Just copied the OEM fuses and soldered the piece of wire between the male spades. I then used the piggy back connectors and put the whole thing back together. Also If I were to do it again I see that Radio Shack has the new blade fuse holders which can be joined together to form a fuse block. You can use the same approach and buss them together and then use the piggy back connectors. Then just mount them to the 1" alumin. strip and remount them. With this design I think I can make the stock plastic fuse covers work.

 

Great minds think alike. That's what I do on mine too.