P38A blend motor

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
kermit_rr said:
Yes I've done the calibration, which cycles from current position to cold, then hot and stops
Click to expand...

Calibration is when the flap is taken in both directions against the stops and the motor is stalled in either direction. This gives the system info about the null point of the pot. Did you line up the flat on the drive flange with the top of the case then line up the arrows on the gear and pot?
 
wammers said:
Calibration is when the flap is taken in both directions against the stops and the motor is stalled in either direction. This gives the system info about the null point of the pot. Did you line up the flat on the drive flange with the top of the case then line up the arrows on the gear and pot?
Click to expand...
The replacement pot i put in had different alignment so the arrows don't line up, it's 90° out so i took that into consideration when i put it all back together
 
Taken it apart again and the pot is working fine, the solder joints are fine and the wires are fine, yet nanocom was seeing wrong values that it wasn't seeing this morning. I wonder if there's a dodgy connection elsewhere...
 
kermit_rr said:
Taken it apart again and the pot is working fine, the solder joints are fine and the wires are fine, yet nanocom was seeing wrong values that it wasn't seeing this morning. I wonder if there's a dodgy connection elsewhere...
Click to expand...
Yep dodgy connection somewhere. Put it back on the car and it worked for a few moments ie. Moved as i changed the temp on the car display, then stopped.
Progress i think, guess what I'm doing tomorrow!!
 
kermit_rr said:
Yes i see the value change but can't see if it goes all the way to zero or not as going thru the menus is too slow.
I did take the lid off the motor while still plugged in and turned the pot by hand, it went from 0-92 without any apparent dodgy readings in between
Click to expand...

0 - 92 sounds odd. Never really played with that module but I would expect 0 - 256 for bits or maybe degrees movement.
 
kermit_rr said:
The replacement pot i put in had different alignment so the arrows don't line up, it's 90° out so i took that into consideration when i put it all back together
Click to expand...

So, does "taking into consideration mean you realigned the arrows, or left them 90 degrees out? they shd be realigned, obv. Or maybe try installing a different pot, since you're back in there. I think, when fitted, mine are showing between 1 and 9k across the wiper and one or other of the reference wires.

Bear in mind that if you have a service book symbol then all bets are off re the motors - HEVAC may try and protect them (eg my RH blend motor feedback problem allowed the LH blend to be controlled by HEVAC, but the distribution motor would not move) are there any gremlins elsewhere?
 
Last edited:
In practice the pot will never reach it's full travel in either direction. The flap stops will prevent that. Calibration gives the ECU a null point to work from. That is the reason for the arrow marks, they place the pot at mid point initially.
 
To find the mid point, i found the max value and divided in half, then set the pot to that value, then put the output drive on with the flat parallel to the side of the case as normal
I do think it's a cable/connector problem somewhere given it now seems to work intermittently
 
kermit_rr said:
To find the mid point, i found the max value and divided in half, then set the pot to that value, then put the output drive on with the flat parallel to the side of the case as normal
I do think it's a cable/connector problem somewhere given it now seems to work intermittently
Click to expand...
Depending on the potentiometer you used you cannot find the mid point like that, some pots operating on a logarithmic scale, you find the mid point mechanically.
 
Datatek said:
Depending on the potentiometer you used you cannot find the mid point like that, some pots operating on a logarithmic scale, you find the mid point mechanically.
Click to expand...
did not know that! it does seem to be a normal scale, just 90 degrees out.. the physical mid point reads around 5K ohms so it must be right?! *must*
 
Kermit - you say cable/ connector problem... fyi I cleared my "RH Blender motor feedback faulty" error by replacing one pin (on the LH motor !!) and the entire connector block - so the solution can be in a non-obvious place. Also POs may have spliced/ repinned the connector, so worth running over all the wiring on the blend motor connector IMHO
 
You must log in or register to reply here.

Similar threads

P
P38
Replies
2
Views
314
brianp38dse
brianp38dse
Paul Coddington
Year 2000 2.5 DT Manuel Gearbox
Replies
11
Views
861
Paul Coddington
Paul Coddington
F
Gearbox selector issue
Replies
2
Views
372
Datatek
Datatek
IandiscoV8
P38A Blend motors installed - heating fixed.
Replies
1
Views
358
Montyjohn
Montyjohn
T
P38A Heater problem - stuck on demist
2
Replies
22
Views
1K
tank93
T
Back
Top