Help wanted re RHS (A/C) radiator fan for GTV6

[AlfaACT]

The GTV6 has two radiator fans, which (on mine) have always operated independently.
The LHS fan switches "on" when engine temp gets a touch over 80 (approx) and "off" soon after - ie when its done its job.
The RHS fan seems to be somehow linked to the air con, as it only operates when the air con is "on", and then it usually switches "on" some time after the LHS one - ie at a higher temp?
[But maybe it is independent of the A/C, and the only conditions that cause it to switch "on" also only occurr when the A/C is on too - ie high ambient temp and low speed (eg city driving).]
Or thats how it was ... !

Now, the RHS fan is "on" even when the engine is cold!
(To save the battery, I temporarily disconnect the power to the RHS fan!)
And when I turn the engine off, the RHS fan merrily powers on ... The LHS fan still behaves "normally" though.

I suspect that there is a temp sensor, separate from the one in the radiator, that senses engine or oil(?) (not water?) temp and operates the second fan. If it's faulty then it might be the cause (I'm hoping).

So my question is:
Is there a separate temperature sensor that controls the RHS (A/C) fan?
  And if so, where is it located?
  If there isn't a second sensor, has anyone got an explanation for the fan's aberrant behaviour ... ?

Thanks,
Peter.

[colcol]

You have your normal fan for cooling the radiator, then the other one linked in with your aircon, so when the aircon compressor swiches on, your second thermo fan switches on, now start up your car and have a look and see if when you switch on your aircon, the compressor is running and your second fan is running, if the aircon compressor runs all the time and your second fan runs all the time, you may have a problem with your aircon, it may be low on gas or just worn out and its not cooling well and your compressor can't keep up and keeps running all the time along with your second fan, i had that problem with the 33 and it has THREE thermo fans to sort out, Colin.

[AlfaACT]

Thanks Colin,

I might be missing something, but ...

The A/C does appear to be working (remember we are dealing with an Alfetta!) The compressor certainly kicks in when switched on - and the compressor has been upgraded from original spec. But I will follow this line anyway as it might be time for a service anyway - thanks.

Is the second fan supposed to switch on immediately when the A/C goes on? I dont think mine ever has worked this way - it only comes on when the temp is high (and then only after the normal fan).

If I leave the car for a week, with the fan disconnected.
Then, without starting the car (ie everything is cold and not running), reconnect the fan - the fan starts immediately. 
So it seems that the fan gets power from a live circuit - independent of the engine, ignition, accessories, air con, etc.
A faulty live switch will explain it (ie its got power but its permanently closed - regardless of the engine being on or hot). [Like some (after market?) turbos with a delay to let the turbo cool before switching off - if the sensor/timer failed they would never (?) shut down.]

So, again, the question: is there a second sensor/switch and where is it?

Cheers,
Peter.

[aggie57]

Does this help?

http://www.gtv6-156gta.be/LaGTV6techniqueEN.html

[AlfaACT]

Thanks Alister,
Certainly some interesting material there.
Now to read through it, to see if I can find the key ... fingers crossed.
Cheers, Peter.

[MD]

Peter,

I am thinking along the same lines as colcol. I think you have a latched on relay or sticking pressure switch. Try disconnecting the wires from the gas pressure switch usually located at the drier assembly (while the fan is running and ignition "on"). This may or may not cause the fan to stop.

Otherwise, locate the relay for the A/C fan,remove it under the same condition above. If it stops,replace it with a known good equivalent relay and try again.

Bear in mind that it can be common practice in older systems to activate the A/C fan permanently when the A/C is switched "on" and that is not a bad thing at all. It should not however come "on" at all if the A/C is not switched "on". Cars without A/C work fine on just the one main fan.

Finger pockers do sometimes wire up the A/C fan to kick in with the thermo fan to supplement the cooling which is a whole other thing but to keep it simple, just try the first two suggestions for now.

aggie57
Great find.

[AlfaACT]

Thanks MD,

Not knowling a lot about A/Cs, I didn't know where to start.

"I think you have a latched on relay or sticking pressure switch. Try disconnecting the wires from the gas pressure switch usually located at the drier assembly (while the fan is running and ignition "on"). This may or may not cause the fan to stop.

Otherwise, locate the relay for the A/C fan,remove it under the same condition above. If it stops,replace it with a known good equivalent relay and try again."

This is exactly the sort of advice that I was hoping for. I will try these suggestions. Bonus is that it now makes (more) sense too. (And I was just about to patent my perpetual motion machine, but now maybe not.)

This behaviour started quite suddenly (after many years of no problems) - so it seems that something has failed.

Also, I dont believe that I am dealing with a "finger poker" - but time will tell.

Cheers,
Peter.

[aggie57]

Does this help?

http://www.gtv6-156gta.be/LaGTV6techniqueEN.html

awesome link.

Too easy - it came from a similar thread on the Alfabb.

[AlfaACT]

Update ...
Well when I went to check things as recommended by MD, and found the battery was flat - despite being on trickle charge - which delayed things a bit!


With EMF back in the erg supply, these are the findings:
Ignition "on" and AC "on" (that means both blower and cooler switches are "on" - compressor clutch heard to engage) (and the errant fan is doing what it shouldn't!) then:

1. disconnecting separately (or together) the power to the compressor or the pressure switch(es?) on the dryer - the RHS fan still merrily whirrs away!

2. However, disconnecting the relay (top right hand corner of fuse box - labeled "F" in Owner's Manual - see pic) - the fan stops!

The relay was looking a little scorched too - see pic.
So on inspection internally it appears that the spring that returns the contact plate has been cooked allowing the plate to just wobble about. Obvioulsy the coil is still OK (which surprises me) So the relay will function for "on" but does not return therefore there is no "off".

So, now to source another relay - its a SEPIA 0433 type 1C according to the markings.
Pins are (from top & L to R): H87; V86, H87b, V85; V30 - See pic
(and it is different to the other AC relay and the normal fan relay! They both have a plain "87" pin in the centre)

Next to determine if it is just a faulty relay or is the relay just a symptom ... ?

To Colin, Alister and MD (in chronological order of posts) many thanks.

Peter.

PS I also found a neat little diagram (that labels all of the AC parts) that might be helpful to others that may know as little about Air Con as me. Yeah it's not yesterday's but thermodynamics has not changed that much since Newton ;-)

[MD]

Yeah ,well done Peter !
Had a hunch that the relay was latched on.
If you cannot locate one of those relays,send me a PM and I might be able to send you one gratis from my spare parts bin. 
I think you will find it wil just be the relay otherwise high current demands would have been blowing fuses. However the fan motor could be getting tired in the bearing department and reluctant to spin and causing a high current load (perhaps) to upset the relay. Check the fan motor by hand and also wire it up independently to a battery and check its operation and if possible its current load.I am guessing 5amps max.

[colcol]

The switch on the receivor drier, thats the black can with 2 pipes going to it is a safety switch, if your aircon runs out of gas and there is not enough pressure, then this switch senses the low pressure and won't give any power to the compressor, if the pressure goes to high, say on a stinking hot day in traffic or you get a blockage, then the pressure goes skyhigh and you would get a rupture at 250 psi, dangerous, so the pressure switch cuts out the power to the compressor, as for the relay the terminal numbers mean 30 = + battery, 85 = - earth, 86 = + switching on \ off, 87 = to accesories, [horn, fan etc], Colin.

[AlfaACT]

Thanks again guys,

A couple more jobs for tomorrow.
MD, I'll try the local boys for a relay, if no luck I might take you up on that offer.
Another look at the relay indicates that the flexi ribbon connecting the plate to the body had fractured, hence I suspect power was coursing through the spring until it failed - I reckon it could have been glowing.

Colin, until I get it fully sorted the AC is gunna stay "off" - even though we have just had the hottest day of the year and it'll be even hotter termorra ;-)  Thanks also for the explanation for the terminal codes, I did a half hearted search for that but no result. What does it mean for the centre terminal, some are just 87, some 87a and mine is 87b?

Cheers,
Peter.

Oh and happy new year to y'all.

[colcol]

Terminals 87 = accesories, eg left horn, 87b = eg right horn, a letter suffix is sometimes added to the terminal number to distinguish seperate parts of the same circuit or to prevent confusion of two circuits that have similar functions, Colin.

[Alan Hopla]

What does it mean for the centre terminal, some are just 87, some 87a and mine is 87b?

The different marking on the centre pin signifies slightly different internal wiring in the relays.
All these relays have pins 85 and 86 to energize the coil.
Pin 30 is generally used to supply power to the relay, and pins 87, 87a, & 87b connect to the item to be powered.
If the relay has two pins labeled 87, then these pins are connected together in the relay.
When the relay is activated both pins 87 will have the power from pin 30 switched to them.
When the relay is not activated the two pins 87 will still be connected to each other.

If the relay has two pins labeled 87 and 87b then these pins are NOT connected together in the relay.
When the relay is activated both pins 87 will have the power from pin 30 switched to them.
When the relay is not activated the two pins 87 will still be isolated from each other.
I think that in the aircon circuit this relay is used to switch the compressor clutch on one circuit, and the second radiator fan on the second circuit.
This means that the second fan runs whenever the A/C clutch is engaged, but that the second fan can still be activated independently when the A/C clutch is not engaged.
If a relay with two 87 pins was used, this wouldn't work.

If the relay has two pins labeled 87 and 87a then these pins are NOT connected together in the relay.
When the relay is activated pin 87 will have the power from pin 30 switched to it.
When the relay is not activated the pin 87a will have the power from pin 30 switched to it.

Alan.

[colcol]

Exactly Alan, if say a normal relay has 2 trminals marked 87 and you connected your thermo fan to one and the compressor clutch to the other, everytime your thermo fan switched on, so would your compressor clutch, and when your compressor kicked in, then so would your thermo fan, not an ideal situation, also don't assume that all relays have the same pin patterns as they don't, Hella, Bosch, Hansa and others have different pin patterns, mix them up and you could and will have a dead short, why can't the electrical relay companies have a standardised pin pattern, i will never know, Colin.