Cooling fan stuck on.

[philfatkid]

Hi all.
Got to work this afternoon, had the aircon on, on the way, when i arrived and turned the ignition off, but the fan kept running, i thought it was normal :duh: anyway when i got in to drive home the battery was completely flat, i have read various posts about the relays and PCB in the control box behind the bumper, and i am going to get at it over the weekend, but my question is, where can i get replacements bits ?
Phil D.

[SD1too]

From what you're telling us Phil, it sounds as if you're going to be looking for a replacement PCB (on the asumption that your diesel engine won't be overheating :D). There are a couple of club members who can probably help you out with parts. In the meantime, you'll know that you need to get your battery on a charger for at least 24 hours. ;)

Simon

[RodgerD]

So that you can continue to drive and whilst parked up without your battery going flat, you can remove the main relay whilst stationary. You will find it in the fuse box which is located under the bonnet. Easier than disconnecting the battery and possibly losing the radio code.

[casperdog21]

check wires on engine temp switch, thats what happened to my car,

[philfatkid]

check wires on engine temp switch, thats what happened to my car,

Where is the temp switch located ? also don't know if it's relevant, but the fan is stuck on fast speed.

[stocktake]

most common cause is a stuck relay in the relay box.

[SD1too]

Where is the temp switch located ?
Phil,

Casperdog21's suggestion would send an "invalid" temperature reading to the ECM which would then run the radiator fan at high speed when the engine is running and for a short time after it's switched off. The easiest way to check the coolant temperature sensor is to activate the instrument pack diagnostics like this (http://www.the75andztclub.co.uk/forum/showthread.php?t=185808). I doubt that this is the problem though for one specific reason: you reported that your battery was flat. This suggests that the fan ran continuously which we know happens when the PCB fails or, as Stocktake says, a relay suffers welded contacts. Personally, my money's on the PCB. :} Either way, it's bumper off I'm afraid.

Simon

[philfatkid]

Phil,

Casperdog21's suggestion would send an "invalid" temperature reading to the ECM which would then run the radiator fan at high speed when the engine is running and for a short time after it's switched off. The easiest way to check the coolant temperature sensor is to activate the instrument pack diagnostics like this (http://www.the75andztclub.co.uk/forum/showthread.php?t=185808). I doubt that this is the problem though for one specific reason: you reported that your battery was flat. This suggests that the fan ran continuously which we know happens when the PCB fails or, as Stocktake says, a relay suffers welded contacts. Personally, my money's on the PCB. :} Either way, it's bumper off I'm afraid.

Simon

I'm not too concerned by taking the bumper off (did it to replace the resistor when i bought the car, and again when i changed my burners in the xenons) but if it's the relay, where do i get a replacement ?

[SD1too]

... but if it's the relay, where do i get a replacement ?
We'll tackle that if you find that a relay is the problem. Open the control box, remove and test them. I bet you they're o.k. :D

Simon

[stocktake]

We'll tackle that if you find that a relay is the problem. Open the control box, remove and test them. I bet you they're o.k. :D

Simon
Double or quits on that beer I owe you Simon? :D

the relay is a simple 4 pole contact when energised, quite a standard item
Jules ( a member on here) can supply a replacement relay ;)

[SD1too]

the relay is a simple 4 pole contact ...
Hi Dave,

Err ... each relay is single pole surely. :shrug:
... quite a standard item ..
The contact rating of the large relay is much higher than standard Dave: 60 amps at 23°C and 40 amps at a more realistic 85°C.

Anyway, my point is that it's too early to be worrying about relay supply when it hasn't yet been established that this is a relay fault.

Simon :D

[stocktake]

Hi Dave,

Err ... each relay is single pole surely. :shrug:

The contact rating of the large relay is much higher than standard Dave: 60 amps at 23°C and 40 amps at a more realistic 85°C.

Anyway, my point is that it's too early to be worrying about relay supply when it hasn't yet been established that this is a relay fault.

Simon :D

:o for pole read pin :) :o

[Jules]

Hi quality Relays have always been available from me PM me for details.;)
I also have PWM's also (both types in my shop)

If your Low speed fan (not sure if you have a later 2 speeder or earlier 3 speeder fitted ??) has been U/S for a while, then the high speed relay (2 speed fan) fails soon after because this 40 amp relay doesn't like a sudden 60 amps being put through it !


The best way of isolating a continuous fan is simply to remove fuse 4 (the only 80 amp fuse) in the bonnet fuse box (2 screws)

No need to disconnect the battery or crawl underneath to unplug the fan harness !!

[philfatkid]

Now, now SD1too and stocktake, no bickering :pillow: i will put you both out of your misery, probably start the job on Sun afternoon, work is getting in the way :(

[philfatkid]

Ok a quick update, and i will hopefully get some advice, with how to proceed,
i finally got to the control box (who the bleeding hell thought this was a good place to mount an important piece of kit) and on investigation found that if a i disconnected the red wire to the relay the fan stopped, so i assumed the relay was u/s, i fitted a new one, reconnected the battery and the fan didn't run, i thought i had cracked it, but oh no, as i was poking around i found that the gold resistor i had fitted a few years ago had been blown to s**te, the post had been blown out of the middle:shrug:, i tried the demist test with the aircon expecting the fan to come on full speed or pulse, but nothing happened, any thoughts ?

[SD1too]

... if i disconnected the red wire to the relay the fan stopped, so i assumed the relay was u/s ...
Unfortunately Phil, removing the red wire proves nothing. The only way you can test the relays is to remove them from the control box and put 12 volts across the coil. You will hear and feel the contacts making and breaking if the relay is working.
... i found that the gold resistor i had fitted a few years ago had been blown to s**te, the post had been blown out of the middle ..
It's best to get and fit a replacement before continuing with your fault finding.
i tried the demist test with the aircon expecting the fan to come on full speed or pulse, but nothing happened, any thoughts ?
With the engine running and air con. operating I would expect the fan's high speed to pulse. If it doesn't, the "new" relay you fitted is suspect.

Simon

[davidcarp]

Hi all.
Got to work this afternoon, had the aircon on, on the way, when i arrived and turned the ignition off, but the fan kept running, i thought it was normal :duh: anyway when i got in to drive home the battery was completely flat, i have read various posts about the relays and PCB in the control box behind the bumper, and i am going to get at it over the weekend, but my question is, where can i get replacements bits ?
Phil D.

I've got a similar problem. The high speed fan stays on even if no A/C on. Got an auto electrician looking at it tomorrow. If he can identify the problem I'll seek advice via the club. As I didn't want to keep disconnecting the battery I removed R4 relay and it still stayed on. Removed FL4 fuse and it went off.

[stocktake]

It is almost certainly the pcb ( diesel only) or the relay (petrol or diesel) :)

[SD1too]

I've got a similar problem. Got an auto electrician looking at it tomorrow ... I removed R4 relay and it still stayed on. Removed FL4 fuse and it went off.
Ah, that tells me exactly what the problem is, but then I'm not trading as an auto electrician so what do I know? ;)

Simon

[davidcarp]

It is almost certainly the pcb ( diesel only) or the relay (petrol or diesel) :)

Can the PCB be changed separately and where is it or do I have to get whole fan assembly? I've had the car for 5 years and don't think the other fans have ever worked ( I've done the 'demist on check' but the fan doesn't come on. I check the temp when driving and goes up to about 87 degrees. Ill have to get the work done for me. What would be involved?Thanks

[stocktake]

Can the PCB be changed separately and where is it or do I have to get whole fan assembly? I've had the car for 5 years and don't think the other fans have ever worked ( I've done the 'demist on check' but the fan doesn't come on. I check the temp when driving and goes up to about 87 degrees. Ill have to get the work done for me. What would be involved?Thanks

It would appear David that Simon has your problem in hand on your other thread, you won't go wrong with his advice. Jumping on another persons thread will only cloud the water for you.

[davidcarp]

It would appear David that Simon has your problem in hand on your other thread, you won't go wrong with his advice. Jumping on another persons thread will only cloud the water for you.

Thanks for your assistance

[HarryM1BYT]

i thought i had cracked it, but oh no, as i was poking around i found that the gold resistor i had fitted a few years ago had been blown to s**te, the post had been blown out of the middle:shrug:

That exploding resistor issue has happened before. Assumption was - that the resistor wasn't properly sealed, water had got in, then the heat had turned the water to steam. The steam built up a lot of pressure, enough to blow the resistor apart.

Best advice is make sure the resistor is a genuine good quality replacement item.

[philfatkid]

Update 2,
Fitted the new resistor, tested the high speed relay (as per SD1too's instructions) this was fine, tested the fan via the demist route, it still didn't work, checked the low speed relay, found it wasn't latching (coil knackered) swapped it for the unused one next to it, and low and behold it worked when tested via the demist route.
My questions are,

1, When i first tested the fan yesterday, after changing the high speed relay, the fan didn't work at all, (this is after originally the fan being on constantly on fast speed, even when ignition was turned off) SD1too said it should have pulsed at high speed, is the reason it didn't, because the low speed relay was u/s ?
2, Is there any way i can test the high speed function, like you can test the low speed (demist test) ? because i don't fancy putting the Blue beast back together only to find the fan doesn't work on fast speed.

Phil D.

[SD1too]

1, When i first tested the fan yesterday, after changing the high speed relay, the fan didn't work at all, (this is after originally the fan being on constantly on fast speed, even when ignition was turned off) SD1too said it should have pulsed at high speed, is the reason it didn't, because the low speed relay was u/s ?
Until the other day I would have said that the low speed relay wouldn't affect high speed operation (on a resistor system), but I'm finding out that the diesel system moves in mysterious ways. Another member had the same problem as you; continuous running of the fan whether air con. was on or off. As part of our investigation the coolant temperature sensor was unplugged. When refitted, the fan had stopped running continuously and when the air con. was subsequently recharged the system worked perfectly. :shrug:

In your particular case, if the low speed relay coil was open circuit the ECM would be able to detect that. It's therefore possible that it could inhibit the fast speed, although that would be totally illogical. However we are talking about computers here! :D
2, Is there any way i can test the high speed function ..
Yes. Remove the trinary switch electrical connector and join together pins 2 (black wire) and 3 (yellow/grey wire). The high speed fan should then be triggered. Your air conditioning will probably have to be charged and in working order for this test to be reliable.

Well done for fixing your own car. Unfortunately it looks like that's another beer I owe to Stocktake. :pillow: ;)

Simon

[philfatkid]

Until the other day I would have said that the low speed relay wouldn't affect high speed operation (on a resistor system), but I'm finding out that the diesel system moves in mysterious ways. Another member had the same problem as you; continuous running of the fan whether air con. was on or off. As part of our investigation the coolant temperature sensor was unplugged. When refitted, the fan had stopped running continuously and when the air con. was subsequently recharged the system worked perfectly. :shrug:

In your particular case, if the low speed relay coil was open circuit the ECM would be able to detect that. It's therefore possible that it could inhibit the fast speed, although that would be totally illogical. However we are talking about computers here! :D

Yes. Remove the trinary switch electrical connector and join together pins 2 (black wire) and 3 (yellow/grey wire). The high speed fan should then be triggered. Your air conditioning will probably have to be charged and in working order for this test to be reliable.

Well done for fixing your own car. Unfortunately it looks like that's another beer I owe to Stocktake. :pillow: ;)

Simon

Sorry for your loss Simon :} as a matter of interest where is the trinary switch located ?
Phil D.

[philfatkid]

Ok Simon,
Update 3, found the trinary switch, shorted out the black and yellow wires, the fan came on but only at slow speed ?
Phil D.

[philfatkid]

Update 4,
Energised the high speed relay with 12v and the fan came on at high speed ?
Phil D.

[SD1too]

...found the trinary switch, shorted out the black and yellow wires, the fan came on but only at slow speed ?
There's something not quite right here.
Update 4,
Energised the high speed relay with 12v ..
How did you do that? :confused:

Simon

[philfatkid]

There's something not quite right here.

How did you do that? :confused:

Simon

Took the relay out of the control box, connected the cables to the fan, then put 12v on to the coil, simples:}
Do you think it might be the PCB now ?

[stocktake]

Took the relay out of the control box, connected the cables to the fan, then put 12v on to the coil, simples:}
Do you think it might be the PCB now ?

Gulp, beer looking precarious :o

[SD1too]

Took the relay out of the control box, connected the cables to the fan, then put 12v on to the coil ..
That's a clever trick Phil. :bowdown:
Do you think it might be the PCB now ?
It looks like it, doesn't it.

Simon

[stocktake]

Dave throws towel into ring..................... :laughing2:

[philfatkid]

That's a clever trick Phil. :bowdown:

It looks like it, doesn't it.

Simon

Necessity is the mother of invention :cool2: where can i get a pcb ?

[SD1too]

.. where can i get a pcb ?
Mr. Jules.

Simon

[philfatkid]

Mr. Jules.

Simon

I will pm him, thanks for your help pal, seem you both may have been right :shrug:

[SD1too]

I will pm him, thanks for your help pal ..
My pleasure Phil. :D

Simon

[philfatkid]

Mr. Jules.

Simon

I'm struggling to track one down, any ideas pal ?
Phil D.

[SD1too]

Phil,

To recap, your slow speed works on the demist test. The trinary switch test triggers slow speed, not fast. Am i right?

Just to check:
Large relay has black & red thick wires.
Small relay has black & grey thick wires.
The resistor has a black wire at each end: one goes to red & black, the other to grey.

Simon

[Arctic]

Update 2,
Fitted the new resistor, tested the high speed relay (as per SD1too's instructions) this was fine, tested the fan via the demist route, it still didn't work, checked the low speed relay, found it wasn't latching (coil knackered) swapped it for the unused one next to it, and low and behold it worked when tested via the demist route.
My questions are,

1, When i first tested the fan yesterday, after changing the high speed relay, the fan didn't work at all, (this is after originally the fan being on constantly on fast speed, even when ignition was turned off) SD1too said it should have pulsed at high speed, is the reason it didn't, because the low speed relay was u/s ?
2, Is there any way i can test the high speed function, like you can test the low speed (demist test) ? because i don't fancy putting the Blue beast back together only to find the fan doesn't work on fast speed.

Phil D.

Hi Phil
Try replacing the small relay that does not work and do all the tests over again and don't forget to drop me that email, by that time you will know more and I will have had chance to look in the shed for control box etc just in case ;)

[philfatkid]

Hi Phil
Try replacing the small relay that does not work and do all the tests over again and don't forget to drop me that email, by that time you will know more and I will have had chance to look in the shed for control box etc just in case ;)

I've replaced the small relay Steve, nothing worked till i replaced this relay, and now only slow speed works, even whilst doing the trinary test.

Your right Simon, slow speed works on both tests, no fast speed, i will confirm wiring this morning, just a quick question, does it matter which way round the wires are connected to the resistor (i didn't think it would so i didn't take much notice which way round they were)
Phil D.

[SD1too]

.. does it matter which way round the wires are connected to the resistor ..
No. They can be either way around.

Phil, one other question, is your PCB green and tan in colour and marked 'Stribel'?

Simon

[philfatkid]

No. They can be either way around.

Phil, one other question, is your PCB green and tan in colour and marked 'Stribel'?

Simon

Yes it is tan and green and has Strible written on it Simon, i have checked the wiring this morning and the large relay(fast speed) has a black and a red wire to it, the smaller relay(slow speed) has a black and a grey wire to it, the resistor has 2 black wires to it, as far as i can tell one of them turns into the red wire that goes to the fast speed relay and the other one turns into the grey wire that goes to the slow speed relay.

[Arctic]

I've replaced the small relay Steve, nothing worked till i replaced this relay, and now only slow speed works, even whilst doing the trinary test.

Phil yes I know you changed the small relay for the one next to it, but did you then change that one that was not working before putting it back into the PCB board, if not try that first, so you then have two known working small replays.

Your right Simon, slow speed works on both tests, no fast speed, i will confirm wiring this morning, just a quick question, does it matter which way round the wires are connected to the resistor (i didn't think it would so i didn't take much notice which way round they were)
Phil D.

No. They can be either way around.

Phil, one other question, is your PCB green and tan in colour and marked 'Stribel'?

Simon

Simon is correct the black wires to the resistor make no difference.

Yes it is tan and green and has Strible written on it Simon, i have checked the wiring this morning and the large relay(fast speed) has a black and a red wire to it, the smaller relay(slow speed) has a black and a grey wire to it, the resistor has 2 black wires to it, as far as i can tell one of them turns into the red wire that goes to the fast speed relay and the other one turns into the grey wire that goes to the slow speed relay.

Phil is your PCB board the same as below in the photo' PS you need to make sure the small relay which as no wires connected to it is also a good one working as it should.

What is written on your control box lid PWM2 or M47 as these boards are different but lets not worry about that yet.

I have received your email.

[philfatkid]

Simon is correct the black wires to the resistor make no difference.



Phil is your PCB board the same as below in the photo' PS you need to make sure the small relay which as no wires connected to it is also a good one working as it should.

What is written on your control box lid PWM2 or M47 as these boards are different but lets not worry about that yet.

I have received your email.

PWM2 is written on the box lid, the pcb is the same as the one in your photo.
Are you saying that the other small relay has to be in place on the pcb ? even though it's not switching/controlling anything ?

[Arctic]

PWM2 is written on the box lid, the pcb is the same as the one in your photo.
Are you saying that the other small relay has to be in place on the pcb ? even though it's not switching/controlling anything ?

Yes I would have thought so, try a good one and see what happens I have also sent you some photo's to your email address.

Think back when before you change the relay over the slow speed did not work, you changed the relay over and it worked, reverse that situation now the fast speed does not work.

Also look at the tacks on the PCB board both sides see if you can see any damage such as this below.

[philfatkid]

Update....
I'm having trouble finding one of the small relays, going to RS this afternoon to find something similar, can't believe a unused relay has to be fitted to the pcb to make the rest of the system operate correctly..... hang on this is a company that thought it was a good idea to put the slave cylinder inside the bell housing, and who thought it would be a good idea to make you take the bumper off to change your burners and work on you fan control box, so maybe it's correct, watch this space......
Phil D.

[philfatkid]

Ok fitted the new relay as per your instructions Arctic, no difference, checked the pcb no obvious sign of damage like shown in your picture, i'm at a loss:shrug:
Phil(increasingly frustrated)D

[Jules]

Just because the PCB looks ok trackwise doesn't mean it's ok.
The utmost care must be taken removing the PCB as they are a very tight fit on the connections.

Sometimes they don't survive being removed from off the relays.:shrug:

The 3rd relay must be in situ even though it's not connected as the ECM monitors the current driving the relay coils.]

Sorry we can't help with a spare PCB.
A year ago we had plenty of spares but scarce at the mo.


Jules

[philfatkid]

Thanks for that Jules, have you got any of the relays, high speed and low speed ? if so how much are they ?
Phil D.

[Arctic]

Ok fitted the new relay as per your instructions Arctic, no difference, checked the pcb no obvious sign of damage like shown in your picture, i'm at a loss:shrug:
Phil(increasingly frustrated)D

Phil.
Right so we could be looking at PCB damage then.

Just because the PCB looks ok trackwise doesn't mean it's ok.
The utmost care must be taken removing the PCB as they are a very tight fit on the connections.

Sometimes they don't survive being removed from off the relays.:shrug:

The 3rd relay must be in situ even though it's not connected as the ECM monitors the current driving the relay coils.]

Sorry we can't help with a spare PCB.
A year ago we had plenty of spares but scarce at the mo.


Jules

Phil as Jules says a good 3rd relay must be is place also, and because he as no spares and I have looked into the box where I have quite a few control boxes with relays and a couple of PCB boards I will be posting out to you tomorrow a control box with the three relays and the PCB board (FOC ) Hopefully it will reach you by Saturday morning.

Fit you wiring from your control box to the one I send that way you have less chance of doing any damage to the PCB.

All I ask is please confirm your PCB in your control box is the same as the one in the photo with the control box below, or is it the PCB board bottom of the three together as I do not want to send the wrong items to you cheers Arctic ;)

[SD1too]

All I ask is please confirm your PCB in your control box is the same as the one in the photo with the control box below ..
Steve; Phil has confirmed that he has the original Stribel PCB (see posts 42 & 43). :}

Simon

[philfatkid]

Ok update ......
Fitted the new control box(kindly supplied by Arctic)this morning, but no different, the fan works on slow speed doing the demist test, but wont run at high speed doing the trinary switch test, tearing hair out starting soon....
Phil D.

[philfatkid]

If the aircon gas is low, would this stop the fan working at fast speed during the trinary test ?
Phil D.

[SD1too]

I certainly wouldn't rule that out Phil, but it would have to be low enough to prevent the compressor engaging because that's the only data the ECM receives. The diesel's PCB is a bit of black magic which we don't fully understand.

You did remember to turn on the ignition didn't you?

Simon

[philfatkid]

I certainly wouldn't rule that out Phil, but it would have to be low enough to prevent the compressor engaging because that's the only data the ECM receives. The diesel's PCB is a bit of black magic which we don't fully understand.

You did remember to turn on the ignition didn't you?

Simon

Yes Si, tried it with ignition on and engine running, what sort of problems am i likely to encounter if i put the car back together without the high speed working ?
Phil D.

Anyone ?

[philfatkid]

Anyone have any thoughts on running my car without the high speed on the fan not working ?

[SD1too]

... what sort of problems am i likely to encounter if i put the car back together without the high speed working ?
It will be needed on a hot summer's day for the air conditioning to work properly. From what I've read from other diesel owners, if you're thinking of crossing the Alps towing a caravan there is a risk of overheating.

But that would be accepting defeat Phil. I'd really like to find out why your fast speed isn't working, and I've thought of another question for you, if you don't mind. ;)

On the PCB there are four thin wire connections: black, blue/red, yellow, grey. On your car, is the grey wire connected on its own or is it on the same terminal as the blue/red wire?

Also Phil, if you put your voltmeter across the high speed relay coil you should see 0v until you short the trinary switch contacts when it should rise to 12v if the relay circuit is being completed.

Just to check, the trinary switch wires you're joining are yellow/grey and black.

Simon

[philfatkid]

It will be needed on a hot summer's day for the air conditioning to work properly. From what I've read from other diesel owners, if you're thinking of crossing the Alps towing a caravan there is a risk of overheating.

But that would be accepting defeat Phil. I'd really like to find out why your fast speed isn't working, and I've thought of another question for you, if you don't mind. ;)

On the PCB there are four thin wire connections: black, blue/red, yellow, grey. On your car, is the grey wire connected on its own or is it on the same terminal as the blue/red wire?

Also Phil, if you put your voltmeter across the high speed relay coil you should see 0v until you short the trinary switch contacts when it should rise to 12v if the relay circuit is being completed.

Just to check, the trinary switch wires you're joining are yellow/grey and black.

Simon

I will check all the above tomorrow Si, and let you know, Arctic is pondering this problem too, via e mail, i'm very grateful for all your help.:bowdown:

[Arctic]

[QUOTE]On the PCB there are four thin wire connections: black, blue/red, yellow, grey. On your car, is the grey wire connected on its own or is it on the same terminal as the blue/red wire?Also Phil, if you put your voltmeter across the high speed relay coil you should see 0v until you short the trinary switch contacts when it should rise to 12v if the relay circuit is being completed.



Photo's below of the wires that Simon is referring to, Arctic

[Richym]

Hey Phil

I am having same problem as you. Old 3 speed fan was totally fried (red wire was starting to get burned). I got new fan from Jules and now have slow speed but still cant get high speed working. I just need to get a new control box and replace to see if thats the problem. Hope you get it sorted and looking forward to hearing more about it.

Thx Sd1 and Arctic for your input. It has gave me a few more thing to think about.

Richy

[philfatkid]

Ok, here goes Si,Arctic,
I checked the small wires on the PCB and the grey wire is on it's own connector, apart from the red/blue wire. I checked the voltage at the high speed relay, with the trinary switch shorted out and i'm only getting 3.7v ?
I know the high speed fan works, because i have rigged up a switch on the dashboard (in case i can't get the high speed fan on automatically) that puts a feed on to my old high speed relay piggy backed next to the fan control unit in a little enclosure, and when i test it the high spreed fan comes on.
48445

Phil D.

[SD1too]

I checked the voltage at the high speed relay, with the trinary switch shorted out and i'm only getting 3.7v ?
Just to check; that was with both meter probes across the coil terminals on the PCB, not between one terminal and a separate earth?

Is your air conditioning fully charged and working? I was helping another diesel owner recently whose fan only worked properly when the air con. was recharged.

I would disconnect your additional wiring and relay whilst we're trying to find the fault. It might be confusing the PCB electronics.

Simon

[Arctic]

Hi Phil.
I am with Simon, maybe best to disconnect your additional wiring and relay whilst we're trying to find the fault. It might be confusing the PCB electronics.

This is becoming very mind boggling as when you check the high speed you say it works, also the slow speed but not via the trinary ? as above I am wondering if it maybe A/C gas I am sure we will get it solved one way or another, Simon is on it I am thinking about it and Dave as is also pondering over it and watching the thread :}

[philfatkid]

The wiring is connected as original, I only altered it to test if the new switch would work. So is getting my air con pressure checked, the next step ?
I thought the trinary switch brought on the high speed fan if it sensed high pressure in the air con, if this is correct, then by shorting the plug out i am recreating high pressure sensed, so bringing on the high speed fan, so it can't be the air con running at low pressure, can it ?

[SD1too]

So is getting my air con pressure checked, the next step ?
There's no need for that Phil. Just start the engine and switch on the air conditioning. If the compressor engages and cold air is produced then the ECM will not be receiving a low or high pressure signal from the trinary switch. What I want to know is whether your air con. works, not a precise pressure reading! :D

What about the 3.7 volts reading? You seem to have overlooked my question regarding how you measured that.

Simon

[philfatkid]

Ok Si,
The air con is working fine, nice and cold, i did measure the voltage across the coil contacts on the relay and like i said it reads 3.7v.
Phil D.

[SD1too]

... i did measure the voltage across the coil contacts on the relay and like i said it reads 3.7v.
Well I don't see how a 12v relay has a chance of operating with a potential difference of only 3.7 volts across it's coil, do you? (The data sheet for the large relay gives 7.2 volts as the minimum operating voltage.) So the PCB isn't doing it's job for a reason which we haven't yet found. Perhaps there's a crack at the connection between the relay socket and the PCB.

Have we actually monitored the voltage at the thin grey wire's PCB terminal? Is the trinary switch signal actually getting there? The circuit shows that the trinary switch earths this wire when the refrigerant pressure rises. So try removing the thin grey wire and attaching a short test wire which is reliably earthed at the other end. Does the high speed trigger now?

Simon

[philfatkid]

Well I don't see how a 12v relay has a chance of operating with a potential difference of only 3.7 volts across it's coil, do you? (The data sheet for the large relay gives 7.2 volts as the minimum operating voltage.) So the PCB isn't doing it's job for a reason which we haven't yet found. Perhaps there's a crack at the connection between the relay socket and the PCB.

Have we actually monitored the voltage at the thin grey wire's PCB terminal? Is the trinary switch signal actually getting there? The circuit shows that the trinary switch earths this wire when the refrigerant pressure rises. So try removing the thin grey wire and attaching a short test wire which is reliably earthed at the other end. Does the high speed trigger now?

Simon

Hi Si,
Not to sure what you mean i should dp, do you mean introduce a good earth on to the wire at the trinary switch end ?
Phil D.

[SD1too]

Sorry Phil, I'll try to make it clearer.

Open the control box and remove the thin grey wire from its terminal on the PCB. The trinary switch is now disconnected from the PCB.

We are going to simulate the action of the trinary switch using an open-ended length of spare wire. Connect one end securely to the now vacant terminal on the PCB, and connect the other end to a good, reliable earth. A suitable earth point would be the thin black wire also connected to the PCB. This wire must remain connected to the PCB during any tests though.

Now turn on the ignition and start the engine. Press windscreen demist or 'auto' mode. Is the fan running at fast speed?

Simon

[philfatkid]

Ok Si,
Tried what you suggested, the fan came on but at slow speed, didn't go on to fast speed.
Phil D.

[SD1too]

Thanks Phil. That must mean that the fault lies with the PCB or the relays.

Is 12v present on the thin yellow wire (next to the grey one)? If it is, I'll have to have a conference with Arctic about this puzzle. ;)

Simon

[philfatkid]

Thanks Phil. That must mean that the fault lies with the PCB or the relays.

Is 12v present on the thin yellow wire (next to the grey one)? If it is, I'll have to have a conference with Arctic about this puzzle. ;)

Simon

When should 12v be on the yellow wire, when the air con is on, or all the time ? or during the demist test ect.
Phil D.

[SD1too]

When should 12v be on the yellow wire ...
Good question Phil, sorry for not being clearer. :getmecoat:

The 12v feed should be present when the ignition is on.

Simon

[philfatkid]

Ok Si, 12v is there, with the ignition on.
Phil D.

[SD1too]

This is getting silly! :o

Time for a summary of the situation so far:

High speed relay operates when triggered with a separate 12v supply.
PWM2 control box fitted.
Replacement Stribel PCB with 3 relays fitted supplied by Arctic.
Temporary owner modifications disconnected.
Air con. working.
High speed relay coil has 3.7v across it (minimum requirement 7.2v).
Trinary switch & wiring ruled out with test link.
12v ign. supply present to PCB (yellow wire).


OK Phil; let's make sure that the PCB has an earth connection.
On a DC voltage range, place the red meter probe on the battery positive post. Place the black meter probe on the PCB thin black wire. Does the meter indicate battery voltage?

If that checks out OK, then it's time to gamble with chance. Wait for the sat. nav. disc drive LED to extinguish, then disconnect the battery for at least 30 minutes. Reconnect and try the trinary test again.

Your patience is appreciated Phil! :}

Simon

[philfatkid]

Hi Si,
Everything is on hold now till Tue, i'm off down to Stratford upon Avon golfing for a few days, so i will resume then.
When you say wait for the sat nav LED to extinguish before reconnecting the battery, i can't i haven't got sat nav :D
The 19th hole here i come, FORE !
Phil D.

[freddie]

Sorry to but in Phil but had a problem years ago problem solved with Sdi s help.
If you need to use the car and don't want to keep taking front off
you could move the control box to under the bonnet.
Tip on pictures from picture 15 of this thread.


http://www.the75andztclub.co.uk/forum/showthread.php?t=109061&page=2

Did not have a FBh so put mine on front of battery box.
http://i1234.photobucket.com/albums/ff412/fgrover/SAM_0274_zpsd0216041.jpg (http://s1234.photobucket.com/user/fgrover/media/SAM_0274_zpsd0216041.jpg.html)


Makes life easier you can still do your tests and use your car.

Solves maybe future problems of taking the bumper of again.

[philfatkid]

This is getting silly! :o

Time for a summary of the situation so far:

High speed relay operates when triggered with a separate 12v supply.
PWM2 control box fitted.
Replacement Stribel PCB with 3 relays fitted supplied by Arctic.
Temporary owner modifications disconnected.
Air con. working.
High speed relay coil has 3.7v across it (minimum requirement 7.2v).
Trinary switch & wiring ruled out with test link.
12v ign. supply present to PCB (yellow wire).


OK Phil; let's make sure that the PCB has an earth connection.
On a DC voltage range, place the red meter probe on the battery positive post. Place the black meter probe on the PCB thin black wire. Does the meter indicate battery voltage?

If that checks out OK, then it's time to gamble with chance. Wait for the sat. nav. disc drive LED to extinguish, then disconnect the battery for at least 30 minutes. Reconnect and try the trinary test again.

Your patience is appreciated Phil! :}

Simon

Ok Si,
All of the above is correct, there is an earth connection to the PCB, disconnecting and reconnecting the battery, itried it, but no difference :shrug:
Any further thoughts ?
Phil D.

[SD1too]

Any further thoughts ?
Yes. I think I've gone as far as I can from a remote computer keyboard. I've been in touch with Arctic who says that the control box he sent you was previously tested on another car, and was working. I think that your car needs a meticulous practical check because the problem is probably going to be something basic which we have all overlooked.

I suggest that you give Jules a call and see if he'd be willing to take a look. He does have a diesel of his own I believe. A quick whizz down the A55 and you'll be there. You can sit on the beach and eat candy floss. I'm really sorry that I haven't been able to identify the fault precisely. From your evidence, it appears that the PCB isn't triggering the fast relay properly, though why this is the case is currently a mystery.

Simon

[philfatkid]

Yes. I think I've gone as far as I can from a remote computer keyboard. I've been in touch with Arctic who says that the control box he sent you was previously tested on another car, and was working. I think that your car needs a meticulous practical check because the problem is probably going to be something basic which we have all overlooked.

I suggest that you give Jules a call and see if he'd be willing to take a look. He does have a diesel of his own I believe. A quick whizz down the A55 and you'll be there. You can sit on the beach and eat candy floss. I'm really sorry that I haven't been able to identify the fault precisely. From your evidence, it appears that the PCB isn't triggering the fast relay properly, though why this is the case is currently a mystery.

Simon

Ok Si,
Thanks for trying anyway, i really can't be ar**d to put the car back together, so i can drive it to Jules and have to take it back to pieces, so i am going to install the switch i talked about earlier, it will feed the high speed fan relay from the old control box, and i will use it when it's very warm and i need my air con, or i'm stuck in traffic on a warm day.
i'm getting a new car in Jan, so it will do till then.
Again thanks for all your help, but sometimes you have to hold your hands up and accept defeat:flog:
Phil D.