610 cooling fans

Hi All,

Are the cooling fans meant to do anything clever, or are they just on/off? The air flow from behind the rad seems pathetic compared to the hurricane generated on a DeLorean.

By "clever", I refer (for example) to my Xantia which under normal circumstances, switches the fans on in series (low speed) then in parallel when very hot and AC on.

Today's sunny but not especially hot, and in chasing down my leak, disovered that only one fan is coming on. I discoverd this AFTER jacking the car back down to bleed the system, so would like to know if it's meant to do that before jacking the b9gger back up again! Thanks!

[phildini]

Well my car when idling and getting hot only one comes on..... but I am a new owner to 610 so would not know for sure. I thought the other fan was for the AC

Is it the left one that comes on on yours?

Maybe the other does come in with AC but it's on the back of the main rad - I didn't notice, just assumed the condenser is full size...

[stephendell]

Condenser is full size, full width of rad and in front of it. Fans behind rad.

[mettersl]

Ok Martin, hope this helps....,
Getting to all this is too hard on the car so I went for the wiring diagram. Mine howls a gale when the A/C and fans are both on- definitely both going.

There are three relays controlling the two fans- described as 1st, second and third stage. These are the three on the left in the nose beside the abs ecu. The fan fuses are next to these relays.

At less than 92 degrees they are off, between 92 and 96 degrees they are on in series (half speed) above 96 they are on in parallel (full speed).

They can also be triggered for up to 12 minutes after power off whilst the turbo water cooing pump is operating- there is another relay beside the ACU (passenger foot well) that controls this.

Page 87-3 to 87-7 of the manual explains (see members area).
The a/c being on also triggers serial operation unless there is over pressure in the gas circuit, in which case the fans go up to parallel operation and full speed. There is also an a/c mode fan fault finding chart on page 62-13

Sounds like you have a fuse (each fan has its own), a diode or fan out if the airflow is low or only one fan is operating, or maybe they are just operating in the serial half speed mode as its not yet hot enough!!

Good luck Lee


.

Hi Lee - thanks a million for this info, very useful, and I'll be on it tomorrow just as soon as I've filled the car back up.....

...yes, a 10 minute trawl around sussex campus looking for a parking space caused an overheat today mucho spectacular too as not content with just popping the valve in the bottle cap, my car decided to blow the top of the cap clean off and create a geyser worthy of Yellowstone. Luckily I found all the parts and snapped it back together.

I sincerely hope I haven't done the HG's in as they were only done just before I bought the blinking car - I've probably worked out why they failed now

Now where is the members area should I be looking?

Hi Martin

This pic might help you to locate the relays and fuses



These following two pics might also help





John

That is absolutely superb, thanks a million!

One thing: Can you tell me from the key for the circuit diagram what/where item R164 is?

Clearly the I II and III relay description is a misleading. If you chase the diagram, you'll note the following:

335 switches the ground to one fan, supplied from fuse 27
336 switches the supply to the other fan from fuse 26

Both these relays' coils are parallel wired so work simultaneously. When off, the circuit puts them in series...

337 is the magic serial relay.taking the feed from fuse 27

It's not electrically possible for only one fan to function at low speed, assuming everything is as it should be. From the feeble behaviour of the one working fan, something has gone high resistance, I reckon.

I know what I'll be doing tomorrow afternoon.... better hope for zero traffic on the way home (not to mention a still healthy engine!)

One thing: Can you tell me from the key for the circuit diagram what/where item R164 is?

Lower diagram just above the battery, slightly to the right.....and it is a multipin connector
I`ll have a look at your other questions when I have a bit more time later

okay, getting to the bottom of things,

With the help of the relay locations and wiring diagram, both fans check out okay with 12v across them by jumpin the relay connections. They do indeed make the sort of row I'd expect on a hot day. I've never heard that sound.

The circuit diagram is a tad confusing when the only key I have is in French Is the R164 connector an 8-way, or does it show the throughput of a 4-way?

I think I'll prolly rig up a bodge that fires both fans on at the low temperature, or even an ignition-fed switch so fire them up so they're on constantly, at least until after the MK classic tour.

Where does the sensor to fire on at high speed actually reside in the engine compartment? Or is it an ECU controlled feed? My AC switch works (raises idle and closes the recirc flap) but there's no gas in the system.

[phildini]

Is it the left one that comes on on yours?

Maybe the other does come in with AC but it's on the back of the main rad - I didn't notice, just assumed the condenser is full size...

It's the off side fan that comes on ( just to avoid any confusion )

Hi Martin,

The circuit diagram is a tad confusing when the only key I have is in French Is the R164 connector an 8-way, or does it show the throughput of a 4-way?

You`r not kidding about the diag......But R164 is a 20 way connector, but for this purpose, there are only 4 pins that we are interested in, as shown in the diag. I have got a diag of the connector if you think it can be of help.

.............but there's no gas in the system.

Now this is interesting.....If you look at the cct, you will see bottom right, item 206, which is the "Air conditioning three function pressure switch".
This switch resides on top of some type of canister, which I assume is pressurised. It could be that if there is no gaz, therefore no pressure, pins B1 and B2 on the switch are not connected,....and as this is the Earth return for relay coils 335 and 336 (pin 2 on each) these relays cannot work, if my theory is correct, the whole fan system will not work proprely.
But I could be wrong
Let me know what you think.

John

[mettersl]

From memory, its the switch in the rad that has two sets of contacts- one at 92 and the other at 96. They also work when the turbo cooling water pump is working
The 92 one looks to be in circuit with the A/C pump relay- my reading of the manual is that they both run on low when the A/C is on and go high when it over pressures.

I wonder if Phildini's has the same issue as yours or if I have mis read the wiring diagram and the description in the manual itself. Or its always possible that the manual is wrong, it wouldn't be the first error that I have found.

I'll have a look at the right hand drive supplement over the weekend- the ABS description is completely rewritten in there and replaces the main manual- its a kind of right hand drive and errata section.

Let us know how you get on.
Lee

Martin, further to my comments above which apply only to the A/C side of things, I thought I would colour up a diag to see if it would simplify things.....No comment !!!
Anyway what I feel could well be worth checking in the first instance is the connector on the CAU at the front of the passenger footwell, as there are three outputs which control the fan circuitry, and I remember another A610 owner having intermittent problems with that connector, and the second is the twin thermo switch connector on the rad, 248 in the diag which could also be causing problems.
From my drawing below, it highlights the circuitry involved in the 12min turbo cooling process having switched off the engin, which is also one time ( there may be other times ) when the fans are connected in series by relay 337, and run at slow speed with 6v across each.
Just for clarifaction, 236 is the Fuel Pump Relay...465 is the Turbo cooling water pump relay...57 is the Fan relay via the CAU...and 37 is the CAU.

Hope this is of interest.

John

Hi All, and ssp John, my apologies for not replying sooner, had the Mk classic tour today having driven up yesterdfay (only one AA call out on the way!) and had to abort at the start due to my clutch hydraulics going very wrong overnight. I also still don't trust my cooling system, but that's another story.

my bodge-fix for the cooling fans to run at full speed from the low temp trigger worked perfectly and I didn't overheat at all despite having a large air lock in the rad (bleed hose is blocked)

Question: Where do other 610 owners see their temp gauge sit on a motorway cruise? Mine hovers between 10:30 and 11 o'clock, and I know from experience that at 11:30+ things go bang!

The AC system switch looks like it works the same as the DeLorean setup. The cooling fans aren't controlled from the AC selector switch but instead off the pressure switches in the AC system itself, which also fires the compressor clutch. The system should cycle on the low pressure switch but there's also a safety high pressure switch to protect things in the event of an over-charge.

Modern systems run a variable orifice and the fans are on constantly.

Originally the series function of the motors would have worked equally, but after many years, a lot of wear and some dirty contacts, one inevitably ends up going faster than the other and I was mistaken that one didn't work - one works much better than the other.

Phil - do check your fan electrics - you can test them individually, but both should work at the same time.

When I get a chance, I'll be testing the series and parallel functions from the rad switch, and that'll speak volumes.

I'd be very interested in seeing a key for all the relays in that diagram