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16th July 2015, 13:42 | #1 |
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A different CDTi fan problem
In a nutshell 2 speed fan with neither speed working, fan runs if you apply 12v directly.
A bit of background, I bought the car recently and noticed no low speed fan, didn't try high speed at that point. A couple of weeks ago I took of the silver resistor, found it to be open circuit and replaced it. Re-assembled, still not working, bridged trinary switch - nothing! As the car isn't my daily I got around to having another look today. Stripped it out and found if you apply 12v to fan it runs, so no motor issues. I have 12v on the connector in the wing, so fuse okay and ground on the other connector. I have checked the relays in the fan control box, by removing them and testing with 12v to coil and continuity across switched contacts. So what am I missing? Am I right in thinking the trinary switch when bridged by-passes every other control, so I'm not looking at ECU or anything horrible? The only thing left that I can think of is the PCB in the fan control box itself. Your thoughts would be appreciated gents - thanks Ray |
16th July 2015, 13:48 | #2 |
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The other thing I forgot to mention, there is a relay in the fan control box with nothing connected to it.
I'm assuming they used the same box for the old 3 speed fan? |
16th July 2015, 14:07 | #3 |
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What is marked on the resistor you have fitted ?
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16th July 2015, 15:23 | #4 |
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16th July 2015, 15:43 | #5 |
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Have you got 12V and ground at the control box itself? And while you're in the box, are the output wires to the fan and resistor showing closed circuit?
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16th July 2015, 15:44 | #6 |
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16th July 2015, 16:54 | #7 | |
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Quote:
In fact if I bridge the relays in turn I get slow speed and fast speed. While back in there I checked the voltages on each of the relay coils and I have approx 5v on all of the coil contacts. I didn't notice when I had them out earlier but do they operate on 5v or should there be 12v there? This voltage is present on all relay coil contacts when the ignition is on, regardless of AC position even with the ATC turned off. |
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16th July 2015, 16:55 | #8 |
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16th July 2015, 17:47 | #9 |
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16th July 2015, 18:02 | #10 |
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