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5th October 2019, 06:36 | #1 |
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It Was on Pab's motor Simon, never got the chance to strip it out and have a look. He wanted it replaced with the two speed version, It was an 04 car and you would have thought it would have been a two speed fan but it was certainly three speed four wire fan that appeared original.
It definitely cycled on and off I have never known another 3 speed fan do this, looking back it was certainly not a high speed. So I believe your explanation is correct. I also believe that the trinary switch called, the remaining two brushes caused the motor to operate and successfully satisfied the trinarys needs and as such shut down until it reach its threshold again. Hence the cycling.
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5th October 2019, 12:38 | #2 | |
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I hadn't thought about it before, but isn't fan cycling logical for all motors? Why would a faulty 3-speed fan run at a higher speed to cool the condenser but not trip off when the trinary pressure dropped? The implication is a faulty 3-speed would run continuously at higher speed while ever the aircon was in use. TC |
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5th October 2019, 13:25 | #3 | |
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Simon
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5th October 2019, 15:32 | #4 | ||
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TC |
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5th October 2019, 17:50 | #5 | |
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"Whatever is rightly done, however humble, is noble." Sir Henry Royce. Last edited by SD1too; 5th October 2019 at 17:55.. |
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6th October 2019, 10:19 | #6 | |
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Dave... Lost a few stones and a Gall Bladder and part of a bile duct and all of my dignity in the suppository incident |
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6th October 2019, 12:02 | #7 | |
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Indeed, but the situation with Pab's car had the aircon fan pulsing at the (low) brush-wear compromised 'medium' speed. Which though unusual is logical. In the OP's case, the aircon fan is running continuously at some speed or other, yet the low and medium speeds have, apparently, failed. The high speed motor brushes are proviing some engine cooling at 112C, so what mechanism is switching them in for the aircon demand? TC |
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6th October 2019, 12:18 | #8 | |
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I can recall a different members car 2.5 v6 and that had symptoms of when the A/C was switched on there was a slight delay of 10 to 15 seconds before the fan started on a slow speed with no pulsing on and off. I thought twas a most unusual action until I opened the relay box to find a pcb . But back to the case in hand, if this is the correct fan and relay then what is happening would indicate a lack of signal from the ecu to the relay box wouldn't it? Yet the temp sensor must be working to allow THE OBD to show temps??? Hope dave6 comes back with more info so we can help diagnose this one, it's interesting
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6th October 2019, 15:51 | #9 | ||
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But Dave6 proposes to replace his 3 speed system with a 2 speed so my hypothesis will never be tested. Simon
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6th October 2019, 16:04 | #10 |
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