P38A blend motor calibration

kermit_rr · Jul 1, 2019

Hi
When you repair/replace a motor, does it need to be calibrated so the system knows the limits of travel?

I repaired my driver's side one and the motor works both ways, but when i put it in place, it blows tepid at best, until i set HI at which point it blows hot but won't go back to cold until i cycle the ignition. I'm guessing the motor it binding because it's trying to adjust too far

blue beasty · Jul 1, 2019

What a dull title

kermit_rr · Jul 1, 2019

Your right, it is was rather!!

Grrrrrr · Jul 1, 2019

kermit_rr said:
Hi
When you repair/replace a motor, does it need to be calibrated so the system knows the limits of travel?

I repaired my driver's side one and the motor works both ways, but when i put it in place, it blows tepid at best, until i set HI at which point it blows hot but won't go back to cold until i cycle the ignition. I'm guessing the motor it binding because it's trying to adjust too far

If it doesn't go back in the same place, yes. Seem to remember MrGorsky having some fun with his after they had been off.

ovalandrover · Jul 2, 2019

if you strip the motors down i think there is marks on the gears that need to line up and also they can be tested with a 9 v battery while out of the car

kermit_rr · Jul 2, 2019

You're right, there are arrows. I've lined these up
I did have an idea that you might be able to put the motor on in more than one hear setting so I'll double check that, ie. find the mid way point on the motor, then try to align to the mid way point on the blend flap. Job for the weekend!
I've seen the nanocom has a calibrate button, so maybe i need to source one sooner than later!!

wammers · Jul 2, 2019

Blend motors calibrate automatically but not very often. Nanocom will run a calibration. Each motor is driven to it's stop in both directions then the Hevac knows the mean centre of travel. It uses this to give various flow rates on blend flaps. And directions on distribution flaps.

Mark Piercy · Jul 2, 2019

All this talk of flaps

kermit_rr · Jul 3, 2019

Had another look...
Set to cold and is fully closed, set to 20c and it opens a tiny bit, set to 28c and it opens up a small amount more. Set it to HI and it opens up fully but sticks and won't move until i cycle the ignition where it backs off slightly and sticks again. Another cycle and it moves all the way back to fully cold.
Rinse and repeat!

stemac33 · Jul 3, 2019

Sounds like you got some sticky flaps

kermit_rr · Jul 3, 2019

Definitely not sticky. Motor off and they move with the slightest touch. Motor off and cycle LO to HI and back again, no sticking, motor works ok, gears not damaged

kermit_rr · Jul 5, 2019

Fixed it! So easy!!
If you replace the pot, the mid point may be in a different place to oem, as the case for me.
This means the arrows shouldn't line up!!

Find the mid point of the pot, then put the big white gear in its proper position, as tho lining up with the arrow, which places the flat parallel to the long edge

Bingo! Sorted

P38A blend motor calibration

kermit_rr

Very

blue beasty

Leaks an prone to bits dropping off

kermit_rr

Very

Grrrrrr

Technician, Bodgit & Scarper Ltd

ovalandrover

Well-Known Member

kermit_rr

Very

wammers

No longer with us, RIP

Mark Piercy

Well fumbled member....

kermit_rr

Very

stemac33

Well-Known Member

kermit_rr

Very

kermit_rr

Very

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