P38A HEVAC

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cornishboater

cornishboater

Well-Known Member
Posts
639
Location
Poole, Dorset
Before I take out the glovebox etc how accessible is the connector for the LH recirc motor (RHD car). This is the only fault that the Nanocom is showing. I have a good spare motor and was thinking of plugging it in and just zip tie it to something to fool the HEVAC into thinking it is ok. I know that getting the old one out is nigh on impossible and I don't really use the recirc function anyway so hopefully this would clear the fault. I don't really want to pull the whole thing apart just to find I can't get to the connector. Ta for any info
I have also asked on the Facebook site but would low AC gas bring up the the pagebook on the HEVAC, seems to be divided answers. The fault emblem has only just appeared although the recirc motor failed years ago, it has been since I did the "O" rings. I have calibrated the blend motors etc and run them through the various settings and they are AOk.
 
i dont think it will work.. on the basis every 200? ignition cycles it does a motor self test.. wind the motor in both directions.. might be a problem if theres no flap to give end travel feedback
 
I used to get the book symbol on my last P38 and to get rid of it I would turn the ignition on/off rapidly.
I don't know exactly what was going on, but I suspect a "sticky" gearwheel (dried up grease) needed a few "kicks" to move through the sticky spot. Anyway, it worked and the book symbol was gone and I would then try and run the AC through all the settings Screen/Dash/Floor etc. to try and loosen things up. Seemed to work for me.
 
cornishboater said:
Before I take out the glovebox etc how accessible is the connector for the LH recirc motor (RHD car). This is the only fault that the Nanocom is showing. I have a good spare motor and was thinking of plugging it in and just zip tie it to something to fool the HEVAC into thinking it is ok. I know that getting the old one out is nigh on impossible and I don't really use the recirc function anyway so hopefully this would clear the fault. I don't really want to pull the whole thing apart just to find I can't get to the connector. Ta for any info
I have also asked on the Facebook site but would low AC gas bring up the the pagebook on the HEVAC, seems to be divided answers. The fault emblem has only just appeared although the recirc motor failed years ago, it has been since I did the "O" rings. I have calibrated the blend motors etc and run them through the various settings and they are AOk.
Click to expand...
A motor on it's own would be no good, you need the feed back pot assuming one is fitted, or if it relies on stall current you need gears and an end stop.
Low or no gas does not show the book symbol on either of mine.
 
Datatek said:
OK so it uses stall current to signify end of travel, either way a motor on it's own is not likely to work unless the motor or wiring is an open circuit and it just need the resistance value of the motor to keep the HEVAC happy. Have you tried driving it with diagnostics?
Click to expand...
Who me?
My motors are perfect I'll have you know. :vb-weee:
 
The saga continues, book symbol now gone and no faults showing, however, there is hardly any air coming out of the face vents. The distribution motor is working as are the blend motors, I have calibrated and tried them under the Nanocom with no issues. Both blowers are running fine. I am scratching my head here I can’t see where else that volume of air can go (or not go) There is however a large volume coming out of the lower floor vents, I am not sure why when under the nano the distribution is working but appears not to be when under the HEVAC
 
cornishboater said:
The saga continues, book symbol now gone and no faults showing, however, there is hardly any air coming out of the face vents. The distribution motor is working as are the blend motors, I have calibrated and tried them under the Nanocom with no issues. Both blowers are running fine. I am scratching my head here I can’t see where else that volume of air can go (or not go) There is however a large volume coming out of the lower floor vents, I am not sure why when under the nano the distribution is working but appears not to be when under the HEVAC
Click to expand...
Is the HEVAC on Manual or Auto?
 
It would flag an error if the pot either reached end stop or didn't move at all. Depends what gears are stripped, but I agree gears are the most likely.

It could also be the output shaft stripped or broken. The motor worm drive the two black gears, when then drive the white intermediate gear & output shaft. The potentiometer gear is finally driven by the output shaft.

1715429964178.png
 
Ta for the info,
To continue, somats up, I can calibrate as mentioned previously with no issues, however, I have forced the distribution motor to face level but it stays blowing at floor level. Therefore I assume that the motor must be at fault although it doesn’t say it is. The recirc flap fault is back because I did a force open and it again flagged the LH as shorted. The fault shouldn’t effect the Nanocom operation though I guess. I wish I had found this when I did the “O” rings last week cuz now I have to pull the bloody thing apart again! I did actually replace this a few years back. I bought the set of 3 from Valeo, anyone know if the other remaining ones will work as a replacement, they look the same
🤓
 
cornishboater said:
Ta for the info,
To continue, somats up, I can calibrate as mentioned previously with no issues, however, I have forced the distribution motor to face level but it stays blowing at floor level. Therefore I assume that the motor must be at fault although it doesn’t say it is. The recirc flap fault is back because I did a force open and it again flagged the LH as shorted. The fault shouldn’t effect the Nanocom operation though I guess. I wish I had found this when I did the “O” rings last week cuz now I have to pull the bloody thing apart again! I did actually replace this a few years back. I bought the set of 3 from Valeo, anyone know if the other remaining ones will work as a replacement, they look the same
🤓
Click to expand...
If you force the distribution flap with Nanocom, you should see not only the motor movement but the feedback. I don't know why you assume the motor is at fault, if you forced the movement and it did not work, a fault would be flagged. To me it sounds like the motor is operating and so is the feedback potentiometer, it's just not driving the distribution flap.
No idea about the recirculation motors as I have never had a problem with them or used recirculation. The LH recirc motor is nowhere near the O rings. The recirc motor is not the same as the blend motors but you might be able to use the parts from a blend motor assembly to make a working recirc motor.
 
The recirc motor failed due to a jammed flap years ago but for some reason is now showing a fault after doing the "O" rings and stripping most of the dash out. Pity about the blend motors not being the same, I still have 2 brand new ones! I will have to strip the stuff out again and have a look, maybe I dislodged something when doing the "O" rings. When you say "see the feedback" where would I see that, when I force the motor it just tells me it is doing it. I might pop the endoscope down the vents and see just what is going on before I rip everything out. It was working fine until I did the rings, such is life I guess, at least the sun was out :)
 
cornishboater said:
The recirc motor failed due to a jammed flap years ago but for some reason is now showing a fault after doing the "O" rings and stripping most of the dash out. Pity about the blend motors not being the same, I still have 2 brand new ones! I will have to strip the stuff out again and have a look, maybe I dislodged something when doing the "O" rings. When you say "see the feedback" where would I see that, when I force the motor it just tells me it is doing it. I might pop the endoscope down the vents and see just what is going on before I rip everything out. It was working fine until I did the rings, such is life I guess, at least the sun was out :)
Click to expand...
I do not know the Nanocom as I have a Faultmate but I do know that the Nanocom shows both the motor movement and the feedback on the same screen. A shot was posted on LZ a short while ago. However if it doesn't log a fault, you could assume the feedback from the potentiometer is working I suppose.
 
Yes Nanocom does give feedback on the pot output. In the HEVAC utility, select the desired percentage, and click "force". another screen will pop up showing the feedback as it drives the motors.

1715501151575.png
 
Thanks, I wasn't thinking about that bit, I have tried that and all works as it should and gives correct feedback, the face/lap shows that it is ok but the air still only goes to the feet no matter where you force it to go. I must have dislodged something when I did the "O" rings. Oh well back to the spanners and screwdrivers!!
 
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