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Old 21st November 2019, 06:18   #61
phenonix
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Took for a run today, seems ok, just want to say a thanks to Arctic and Simon for their help.
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Old 21st November 2019, 08:46   #62
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Originally Posted by phenonix View Post
... seems ok, just want to say a thanks to Arctic and Simon for their help.
Thank you Joe for your kind message to us both.
Your case was a strange one and I still don't understand it but I'm glad that your repair worked!

Simon
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Old 21st November 2019, 10:42   #63
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Quote:
Originally Posted by phenonix View Post
Took for a run today, seems ok, just want to say a thanks to Arctic and Simon for their help.
Hi Joe.
Great to hear you got it running as it should be, do a few runs with the OBC set at 19 then 7 noting the temperature on the screen, park up and let the car tick over while watching the temp when it reaches 100 -101 see if the fan kicks in on slow speed to bring down the temp to about 95-96

It may well have been one of the relays you changed, let us know if you try the above.
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Old 21st November 2019, 11:25   #64
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I'd suggest the first clue to the connumdrum is in the Demist Test when this question was asked (post 41):
Quote:
Originally Posted by stevestrat View Post
Does it run continuously or cycle on and off every 10-15 seconds?
and Joe's answer:
Quote:
Originally Posted by phenonix View Post
Runs continuously.
The very first time I switched on after fixing, it did stop and start every 15 seconds.
About 2 or 3 times. I turned it off and restarted, then it runs continuously but only when demist is pressed
Then (post 47):
Quote:
Originally Posted by phenonix View Post
Still kicks in at 105, turns off at 101-102, drops to 97.
I know everyone says these fans are loud, but this one is Very loud, in a powerful way.
Any possibility high speed only is starting????
And post 60:
Quote:
Originally Posted by phenonix View Post
Changed the resistor and relays.
Now it comes on at 99, then drops to 97....so all good so far.....
Normal speed, nice and quiet, no rattles or noises.
Wonder why the demist test worked though?
So what's going on? In essence, the silver resistor on the fan Joe fitted had indeed failed. The first Demist Test gave a 'fail', which apparently changed to a 'pass' after switching off and repeating the test.

What happened here is the trinary tripped on the emergency aircon over-pressure fan speed (speed 2) because the refrigerant had already gotten too hot from the earlier test. This overheating/over-pressure was probably exacerbated by the very high ambient temperatures currently plaguing Australia and a failing/failed condenser matrix. So I'd suggest Joe also checks the condition of the aircon condenser, which if poor will need replacing.

It would be informative if Joe would report on his aircon performance now that speed 1 operates correctly. From what's reported in the news, he'll certainly need it.

TC

Last edited by T-Cut; 21st November 2019 at 11:27..
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Old 21st November 2019, 13:16   #65
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What happened here is the trinary tripped on the emergency aircon over-pressure fan speed (speed 2) ...
If true, this means that the fast speed of a 2 speed system triggers at 105 degrees and not at 112 degrees as we believe at the moment. I pointed out earlier that 105 degrees is the point at which the medium speed starts on a 3 speed system and as the corresponding wire from the ECM has no physical connection to a 2 speed control box, no relay can be energised in that box.

In another thread MarinaBrian said that ECM coding can be changed to suit a 2 speed fan, the implication being that the 105 degrees switching is then applied to the fast speed relay. When I asked whether he had proved this by practical means, no reply was forthcoming. I therefore conclude that he hasn't.

There is an MGR technical bulletin which warns dealers that T4 can indicate a fault with a 2 speed fan system and that fault is that medium speed has failed. That implies that the switching points are the same whether a 2 or 3 speed fan is fitted so we're back to why Joe's fan started running at 105 degrees.

We really need to wait for a KV6 owner with a mildly overheating engine and a 2 speed fan with the instrument pack diagnostics activated to tell us at what displayed temperature the fast speed cuts in. Up until now, I'm sure that we've had many reports of the temperature gauge shooting to maximum which we've diagnosed as a failed slow speed resistor. If the fast speed had cut in at 105 and cut out again below that temperature (as Joe reported) then the result would surely be a cycling fan at high speed, not an overheating indication.

The question is far from resolved.

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Last edited by SD1too; 21st November 2019 at 13:19..
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Old 21st November 2019, 14:08   #66
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As I see it, the 2-speed system switches to Speed 1 for the duties provided by 'low' and 'medium' speeds of the earlier system. Speed 1 appears to be faster than the earlier fan's 'low' speed and provides sufficient airflow for 'medium' speed duty. It could be argued that a 2-speed system 'overkills' the 'Low' speed fan duty. I recall that Arctic uploaded a video demonstrating T4 tests of a resistor controlled 2-speed. He trips Speed 1 when the T4 'Low' speed test is applied, then Speed 2 using the 'High' speed test. Unfortunately, he doesn't show T4 and the 'Medium' speed test on this fan. This will answer the question and I guess Arctic will know.


EDIT: I see Arctic's T4 tests were on an isolated fan not installed with an ECU, so perhaps the T4 would be invalid for the medium speed test?


TC

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Old 21st November 2019, 16:51   #67
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As I see it, the 2-speed system switches to Speed 1 for the duties provided by 'low' and 'medium' speeds of the earlier system.
Indeed, that is our current understanding prior to Joe's thread. On a 3 speed system "low" runs at 100 degrees and "medium" at 106. That means that if speed 1 (on a 2 speed system) covers both these, it must trigger at 100. This didn't happen according to Joe's account. His coolant temperature rose to 105 before the fan started running.

So your logic, fine as it is, unfortunately doesn't explain what Joe reported.

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Old 21st November 2019, 20:15   #68
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Quite so, so it seems current understanding isn't right. However, if the 'low' speed duty is covered by Speed 1 and the old 'medium' and 'high' duties are covered by Speed 2, then I think it all fits. This proposal would also explain why several observers over the years have reported 'no difference' between the medium and high speed T4 tests on a later 2-speed system. Clearly one or the other and simply by replacing the resistor, Joe got things back to normal.


TC
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Old 21st November 2019, 20:24   #69
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Quote:
Originally Posted by Arctic View Post
Hi Joe.
Great to hear you got it running as it should be, do a few runs with the OBC set at 19 then 7 noting the temperature on the screen, park up and let the car tick over while watching the temp when it reaches 100 -101 see if the fan kicks in on slow speed to bring down the temp to about 95-96

It may well have been one of the relays you changed, let us know if you try the above.
Hi Arctic,
Did this test and performs exactly as above, thanks again.
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Old 21st November 2019, 20:29   #70
phenonix
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Quote:
Originally Posted by T-Cut View Post
I'd suggest the first clue to the connumdrum is in the Demist Test when this question was asked (post 41):
and Joe's answer:


Then (post 47):


And post 60:


So what's going on? In essence, the silver resistor on the fan Joe fitted had indeed failed. The first Demist Test gave a 'fail', which apparently changed to a 'pass' after switching off and repeating the test.

What happened here is the trinary tripped on the emergency aircon over-pressure fan speed (speed 2) because the refrigerant had already gotten too hot from the earlier test. This overheating/over-pressure was probably exacerbated by the very high ambient temperatures currently plaguing Australia and a failing/failed condenser matrix. So I'd suggest Joe also checks the condition of the aircon condenser, which if poor will need replacing.

It would be informative if Joe would report on his aircon performance now that speed 1 operates correctly. From what's reported in the news, he'll certainly need it.

TC
I've tried my Aircon and it seems to be cooling exactly as before (which has never been super cold since i bought the car)
My air condenser looks fine, to the best of my knowledge, its not the original one, as i replaced it a few years ago.
I'm doing all my maintenance in an underground garage, nice and cool, so not affected by our high heats, just a look a smoke from the bush fires in the air, which are a long way away from where i am, luckily.

Last edited by phenonix; 21st November 2019 at 20:37..
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