330 GTC fans relay

Hi F Chatters, Hi Romano
I began a thread with Turbo Joe/Romano about a 330 GTC electrical wrongly in Boxers section (it was following another discussion on a 512BBi...), so that I follow up here.
My situation is that my 330 GTC radiator fans don't start when hot and I could see that the power fuse (N°16, while excitation is separated on N°10 fuse) for this equipment was not fused but melted/storted, due to too high temp, in a way that the contact was no more efficient which explains cooling failure.
I came to troubleshoot as follow:
- check thermo-contact on excitation loops which closes (click sound) normal by by-passing to earth
- check each Lucas fan individually: running OK with 4A which is normal for 36W spec
- but when circuit ON thru relay, with thermo-contact by-passed) the Amps (measured with Amp clamp) is at 40 to 50A between the 2 fuse supports on the copper bus which is far too high (should be around 10A) and explains fuse frame melting
- continuity of positive wires to fans looks OK without ohmic loss to earth
- the 2 copper contacts holding N°16 fuse look fine, as all others, with rivets firmly set on the bus
- putting OFF one fan to identify if one fan wiring would be faulty: the same: 30A circa per single fan ON: too high
- dismantle of the relay LUCAS SR6 (which is not easy: take off battery, dispose the relay because connectors not accessible, necessary disposal of electrical panel to remount the relay...) and checked on a bench and lamp test: excitation works and power closes circuit when excited.
I should have tested the relay anyway with another Bosch 20A on my stock, but I remounted the whole panel/relay.
Because it seems that the relay itself is the last piece of the puzzle which could create too high amperage in the circuit when closed, even if a test under 1A is positive.
Before doing this last step verification (disposing all again), does any FChatter has an experience of this kind and any other suggestion I would have missed?
Thanks a lot,
Jean-Paul

 

I think the contact in the relay is not good anymore? you write you dismateled it. so when you only use a test light this will not drop much power. why not put on 1 fan with wire extension. then you see more. and when all is ok then is the the electrical wiring somewhere something not ok.
what will happen when you put instead of the fans a testlight on? would be worth a try.

 

Per your 09/66 OM schematic, there are two relays involved in running your radiator fan motors -- relay 30 (relay for radiator electric fans) and relay 29 (air conditioning relay, on demand). I believe that they've drawn the internal construction of relay 29 backward on your OM schematic, but the way it works is:

radiator thermoswitch open (coolant cold) and AC "on" = relay 30 unenergized, relay 29 energized = only the radiator fan with nero positive wire runs

radiator thermoswitch closed (coolant hot) and AC "off" = relay 30 energized, relay 29 unenergized = both radiator fans run

radiator thermoswitch closed (coolant hot) and AC "on" = relay 30 energized, relay 29 energized = both radiator fans run

Anyway, just wanted to warn you that if you do next look into the relay operation (and you probably should), you need to check that both relay 30 and relay 29 are working properly.

 

thanks Steve,
yes I noticed that twofold function when A/C exists on the 330GTC (A/C was an option), it is the same for my another 512BBi.
Here, no A/C on this car: only the relay 30 which is a Lucas CR6.
The situation is here more complex at the moment because I just made a temporary streamlined wiring by feeding directly a single fan positive to battery positive, without any relay (negative on car's earth), nor connection thru the fuse box, I found 50A on the Amp clamp (clamp around one wire): far too high.
Conclusion: the Lucas CR6 relay is may be not at stake!
Another trial: with exactly the same circuit, wires, but alimented on another mobile BOSCH 70Ah battery: 20A reading???
I have no experience to say if my car's battery has got some problem to give such a difference?
Next step will be to install my temporary Bosch battery on the car, as main, to see the Amps .
Anyway 20A for a single fan engine, Lucas given for 36W on OM, is still far too high.
On top of that when I checked at the beginning the fans I was reading 4A on the same clamp which is normal finding.
So, since my Amp clamp is old and not sure covers DC, I will do other measures with a new Amp clamp/multimeter on Friday to be sure of the meter.
Even if the measures indicated are not very exact, one thing for sure is that both fans on continuous operation melt the fuse support
Thanks for your assistance, even if I must carry on my homework, will be welcomed.
best,
Jean-Paul

 

Dear Chatters, Sam, Steve & Romano who contributed recently to this thread dedicated to radiator fan electricity troubleshooting.
I now get a good Amp clamp (tested on a bulb: OK).
I did measurement on a first testing battery BOSCH 67Ah old and probably "tired", no relay, direct feed U= 11,5V: 5,0A per single fan (the same for the other fan)after 30s so could be OK for a supposed 36W fan (ie 3A) but with wires/crocodile connectors, age.
But, when back to the car's battery with an exterior same simple 2 wires circuit, U=12,4V: horror 9,7A!
I thought that could be due to this battery which had been too hot in the engine bay when the engine cooling circuit boiled, with something in default inside.
So, third test with another VARTA battery( good condition) U=12,9V: 9,8A, far too high for a single fan.
4th test with another old battery but relatively good condition to start an E-type, U=12,5V: 9,5A same too high amperage.
Note that both fans give individually the same Amps measures.
Lastly, 5th test, to check with the car's regulator, I started the engine with, idem, external positive wire , direct, to clamp the Amp clamp, U= 12,2V (500RPM) : 9,5A.
6th test: with normal wiring configuration, relay on duty, at 500/600RPM (engine idling cold) U=12V and 8,7A per single fan wire (with both fans ON), but Amp clamp positioned around the LH positive wire of single fan alimentation.
In this test, with both LH and RH wires coming to Lucas relay and #16 fuse we are around 17A far too high on a continuous operation with same potential fuse support storting and cut-off. No drive this way possible!

Conclusion: it is as if the fans are very sensitive to voltage: at 11,4V: 4,9A, but between 12,2V and 12,9V: Amp comes always around 9,7V (always after the starting period for steady running), whereas it should be 4A for a nominal 12V.
Question: since I am not familiar with DC electric motor winding, it looks abnormal that the A consumption nearly doubles by passing from 11,5V to 12,4V?
Or is it linked to battery condition, but I don't think since the battery of the last 5th test was with a battery which is normal, never been hot.
Any idea or expertise would be welcomed, before probably deposit the fans and have electrical engine check/repair by a specialist.
thanks a lot,
Jean-Paul

 

One difference may be that an incandescent filament bulb has a very "clean" (constant) DC voltage waveform; whereas, a switching brush DC motor may not. Most handheld multimeters can measure up to a 10A DC current -- I'd trust that more than a clamp-on gizmo. Something else you might try, if your clamp-on device can measure AC current, is to measure the AC current draw of each motor. If it reports a high AC current value = that would increase my distrust of its DC current measurement. Your reported large change in motor current for such a relatively small change in motor voltage doesn't make sense to me.

 

you mean amp, not volt

you may meassure the amp before and after the relay, then you can eliminate those or find the mistake

 

Thanks Steve for this quick feedback.
Reading your comment, I just made another measure with the multimeter (changed the internal fuse which was out) in serie (spec 10A max).
Sorry, but the Amp values are exactly the same as the ones with the other new Amp clamp, ie circa 9,5A after 30s for all batteries above 12,4V.
For me too, it it doesn't make sense, but it is after double-checking with 2 different meters.
So, if no other idea/comment, I think I must prepare myself to find a automotive electricity motors repair company, and dispose the 2 Lucas 3GMGC fans (hope it passes with blades thru the space below the grill...
Jean-Paul

 

# Romano,
Yes sir lease read 9,7 Amps.
Otherwise no relay is at stake with the 4 trials on different batteries with direct wiring for both positive and negative connectors on fan: you can't do simpler...

 

And it measures the same much lower current at the slightly lower voltage? Seems a bit strange to me that both fan motors would measure the same improper values, but maybe stranger things have happened...

 

Yes it is strange, but the wiring cannot be more streamlined as if each fan would be tested outside of the car, on a bench: one battery 2 wires with online fuse connected to fan’s terminals!
If no idea else, I take of the fans for winding and bushes inspection. thanks again
Jean-Paul

 

jean-paul
you may test the amp also on the negative side. I think until now you only tested on the positive side?
I not have the wiring diagram from this car. do you have it? if so you may send to me that I may look what else it could be.
a possibilty could be that when the fans switch on there is voltage going back to the AC and the compressor magnet turns on?
what happens when instead of the fans you put on plus and minus a bulb with 21 W?
all very strange.
if you have time you may come to me ( one way more than 800 km ) and I will have a look at? before I went in december last year to thailand an other f-chat member visited me from finnland with a TR gearbox in his car and I helped him to change 1st and 2nd gears. until now I found all electricity problems, also other garages sometimes come to me to let something fix because they not can go on without a laptop
but I think we can manage this problems here at f-chat with the help of others. because you have the right tools and know what you do. but a wiring diagram would be really great.
romano

 

Hi Romano,
I try to join the OM where the electrical diagram appears, but too heavy. ON internet you find easily 330 GTC owner's manual.
My car has no optional A/C devices.
Anyway, as I mentioned earlier, my last test have been conducted directly from an auxiliary battery to the fan connectors with 2 external wires (A measure on both + & -) without any relay or car's device. To conclude that with battery delivering 12,4V and more, the Amperage of a single fan is around 9,5A after stating time, where it should be circa 4A for 36W!
At 11,5V, it is relatively OK with 5A .
As Steve was pointing, it is strange that both fans demonstrate this too high amperage, but it is.
So, except if I missed some point or any new idea to troubleshoot, I am to dispose the fans to be checked by a specialist in DC automotive motors; I think there is no else issue.
Jean-Paul

 

you may meassure the resistance between the 2 connectors ( plus and minus ) and the fans

what you mean under "stating time"?

 

Ok. Read: starting time means after the amp is stabilized

 

starting makes sense, but not stating, that is why I asked

 

Wonder if it has anything to do with the age of the Lucas fan motors? It is a bit strange that both read the same amp draw when individually connected to an external battery.

I put my old Lucas fans in a box and replaced them with Spal 8-blade fans. New fans w/ better air flow. I also have my fans run continuously when the ignition is turned on. I have both the a/c and temp relays but don't use them. The car isn't driven much in winter. I want the engine to keep as cool as I can for spring/summer/fall driving.

Also replaced the alternator with a 60 AMP AC/Delco unit and put the original alternator in another box. Not going to win any show awards but it makes my GTC a better driver.

 

Thanks SCantera for your experience reporting,
At the end, both fans, under normal car's battery take 8,5A for 12,6A, and I don't think there is big default on it, just old compared to a nominal of circa 4A if new @12V.
I am at the conclusion that with both fans running I am at 17A with 30A fuse cold on finger after 10mn: it is reasonable amperage and I will finally continue with them since they blow a lot.
The relay Lucas is doing well and the problem when the radiator boiled out was that the fuse plastic support melt and lost contact bringing fans OFF.
But, as you suggest, I will draw an additional wire with interruptor under dash to be able to switch them ON, on demand.
My other concern is that the present temp sensor gives false information (indicates 70°C when 90°C real!), so that I just tested a new sensor partly plunged in a kettle, with wire extension from temp wire, which gives normal indication in connection with the gauge on dash.
So that I will change the sensor asap.
Afterwards should be OK.
Best regards,
Jean-Paul

 

The fuse block set-up in the car can be problematic. Periodically I check the contacts at each fuse to make sure they are tight. When I had my engine re-built I also had a new wiring harness and fuse block made by my shop in Naples. Lots of heat and vibration on the firewall makes the fuse block a weak link in the system. Glad you are making progress through your persistent diagnosis!

 

OK, so this may be a stupid question, but….

I’m replacing a junction block on my 330 GTC fuse panel because it got hot and….melted a bit. I believe this was due to a failing ignition relay which has since been fixed (badly word contacts, cloth wrapping over winding had come loose and was interfering with the operation, etc). While I has the fuse panel off the firewall to be able to get to the nut on the back of the junction block bolt, I have also opened the other big relay and clean it’s contacts (horn relay). I’m thinking of replacing the two fan relays since they are older and, well, since I’m in there anyway….you all know the drill.

Here are the existing fan relays:

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here are the relays I can find to replace these:

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Note the swapping of terminals 85 and 86.

The question is…should I also switch the wires (move wire from old 85 to new 86) or connect them in accordance with the numbers on the relays (attach old 85 to new 85)? I have the wiring diagram for the new relays, but not the old relays.

Thoughts?

 

The polarity of the 85 and 86 connections only matter when there is a diode in the circuit (either inside the relay itself, which is usually how it is done when a diode is present, or in the wiring). It probably won't matter in your case.

 

Thanks…I thought that might be the case. I removed the relay and looked at the terminals and they are in really good shape, so I don’t think I will replace them right now. I cleaned the terminals with sandpaper and applied some DeoxIT and put the wire connections back on and reattached the relays to the fuse panel. All good. I will buy a couple of spares just to have them in case.

 

Clean the wiring connector too

 

I did, thanks!