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Hello, back again after some months...
I had repaired a blend motor a year back, but now the distribution stopped working and the right hand side only blows hot, and I have fault "right blend motor short to positive".
Had a new set of Valeo motors here so wanted to put them all in to have some peace....
Before ripping the old ones out I wanted to check the new ones so plugged them in (without installing them yet) but still the book symbol comes on after 1 sec. and the same fault appears !
Tried clearing fault with Nanocom but comes back (or rather stays). Tried the 10 sec. remove plug trick but comes back.
I even tried a different HEVAC Unit but the same thing happens so it can´t be the connectors either...So two motor sets and two HEVAC nits in any combination......
I am now at loss what the hell that could be...something in the loom to the HEVAC.....????
Help and hints are greatly appreciated, I am slowly going insane with that car....

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When the HEVAC is first powered it drives the blend motors from one end of the travel to the other to check the feedback. With them not connected they travel further than they should so will flag an error.

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Hi, thanks for the quick response...
The motors don´t move every time when I turn the ignition, neither the old nor the new. Only around every tenth time or so only one motor will move a little. Onyl once all three moved but only a few seconds. Seems random...
EDIT: Also the book symbol always comes on about half a second after the HEVAC powers up....

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If the symbol somes on that quickly it is failing the pre-test. Pretty sure the motors should run every time you start up, or at last i never notice mine not do it. I had problems with a blend motor once (well, I have had a few in my time, but the wierdest one was only corrected when I depinned the old connector for the blend motors and replaced with a new one ( which you can find off ebay). Do the flaps move unobstructed? I also had to put a self tapper between the halves of the heater box on another occasion to allow the flaps to move more easily

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Dear All,
I had a refurbed HEVAC unit that I could not get to work with all new working servos and flaps etc and eventually Marty managed to find some deeply embedded error code.

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Hello everyone,
Thanks for all the input, I managed to solve the problem but am not entirely sure why....
I measured the resistance across each motor and one (the right blend motor that was giving me the errors) stood out with different values than the others and also the new ones.
So I depinned the connector, left the left blend motor in and installed two new right motors and the new connector.
Then the book symbol disappeared.
After calibrating the motors and testing their movement with Nanocom I reassembled everything and now everything works fine.
I just hope it stays this way but not knowing exactly WHY it now works doesn´t give me much confidence that the problem will be solved forever....
The p38 is really a Zen master putting ones faith to the test..............
Thanks for the input !
Max.

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Well, depending which wires you were measuring your resistance on - the blend motors have a motor, and a potentiometer - the pot resistance varies as the motor moves, which is how it signals to the ECU where the flaps are. If the pot was not working/ had been reassembled incorrectly/ or the blend motor was powered while off the heater box - then the resistance value wd show to the ECU as being out of range and it would fail the pre-test.
I think you should probably be ok now - fingers crossed..

Where in Germany are you? I'm frequently in Frankfurt

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I measured the resistance across brown and black, so the motor itself.
Till now the fault has not re-appeared....
I´m near Hamburg, so up north :-)