blend motor or hevac problem?

Right been at this most of the day.
Connected nanocom and got a list of faults through, one of them being the RH blend motor potentiometer, and motor open circuit.

So pulled the blend motor off and made sure the blend flap was free, ok. Them opened the blend motor back up. Turned on the ignition and the motor started ran one way then the other. Ok. Checked the potentiometer resistance, not reading properly. Soldered a new potentiometer on. Re-assembled.

Cleared the faults and got the nanocom to recalibrate. Fault came back. Tried to get the nanocom to force the rh blend motor to any percentage and it wouldn't, but i could hear another one running behind the dash, strange, I don't know. So I pulled it out again and it had moved but stalled mid way.

Tried to get the nanocom to move just the motor, wouldn't move, every time I try and force the rh blend motor another one moves somewhere under the dash. Turn ignition off, on it worked again. I was begining to think crossed wires so pulled rave out and checked wires ran to the right connector on the hevac unit, they did. Head scratching. Why the hell does it work when you cycle ignition but the nanocom won't force it.

Whilst trying to force it I can twiddle the potentiometer and get a percentage reading. And strangely another one moves?

Blend motor, hevac, nanocom?.

Nanocom forces the others blend motors fine.

You may have found a fault with nanocom, someone else with similar device may help you with answer

Yeah, was hoping somebody would. I am thinking I trust the nanocom, so far. I just wish I could find a motor to replace the one inside the blend motor and save some cash. It's daft how much they go for. Tempted to buy 3 and just splice one in and keep the rest as spares.

Island sell singles....

Anyone know if you can buy just the 12v motor that powers the blend motor?

the blend motors strip gears, there is talk of a compatible one on peugeot that seems more robust-look on rangerovers.net

Looked at the Peugeot one, will it work? I don't know. It is cheaper to buy. Found it on a parts website a few weeks ago. Can't find it now. New it was 37 plus vat and delivery. Hmm what to do, look out for a cheap blend motor.

Tell bbs so they can do the same checks and confirm the nanocom

cljcars said:

Looked at the Peugeot one, will it work? I don't know. It is cheaper to buy. Found it on a parts website a few weeks ago. Can't find it now. New it was 37 plus vat and delivery. Hmm what to do, look out for a cheap blend motor.

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It would be dependant if it is a servo or stop to stop stall and the potentiometer resistance

The Peugeot one is reputedly the same Valeo part as the one on the P38, I have the part number somewhere I think if you need it.

If you could find it that would be great, cheers datatek.

Just to add, I noticed the hevac unit was dated 1998, mines a 1996, last of the gems according to the engine ecu. Did they change the hevac units at all?

cljcars said:

If you could find it that would be great, cheers datatek.

Just to add, I noticed the hevac unit was dated 1998, mines a 1996, last of the gems according to the engine ecu. Did they change the hevac units at all?

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Just changed out my HEVAC and found it was made in 1998 too, car is 1995, changed out with one from 1996 car made in 1996 everything works perfect, yes there's difference i read somewhere with mine it sorted the outside temp reading which was wrong every second time ignition was turned on, other differences Maybe.

cljcars said:

Looked at the Peugeot one, will it work? I don't know. It is cheaper to buy. Found it on a parts website a few weeks ago. Can't find it now. New it was 37 plus vat and delivery. Hmm what to do, look out for a cheap blend motor.

Click to expand...

I have 2 pug (406 if l remember correctly) blend motors in my Range, no problems since fitting them...


http://www.valeoservice.co.uk/ Web Catalog............top right

Strange, my outside temperature sensor reads odd sometimes, -40 mostly then jumps back to normal. Nanocom didn't pick it up as failed so I presume its got a bad connection somewhere. Got to get the bumper off to get at it though, so it can stay the way it is for now.
This blend motor is the only fault left that I need to fix before regassing the ac. Driving me mad.

Cheers for the link zzr1200 much appreciated.

This looks like it. photo looks same, is it?


509225 Control, blending flap
From MY: 05/1997 To MY: 06/1998
To Ch.No.: 7888

out side temperature will either normally be a faulty sensor- either behind bumper or by wipers depending on age of p38. That said I had similar and it turned out to be the hevac unit it's self

I am thinking/hoping its not the hevac unit. New blend motor first then see how it goes.

I think I will contact BBS about the Nanocom just to confirm its ok, still its strange that when I try and force the RH blend motor another one moves, perhaps the hevac unit is knackered and there is nothing wrong with the blend motor.

Had a reply back from BBS regarding Nanocom, software is based on Faultmate MSV-2 systems which has been around for a long time with no
reported issues so they are confident that in this instance the software is
not a problem.

So that leads me to believe that the blend motor motor is knackered or Hevac ecu.

cljcars said:

If you could find it that would be great, cheers datatek.

Just to add, I noticed the hevac unit was dated 1998, mines a 1996, last of the gems according to the engine ecu. Did they change the hevac units at all?

Click to expand...

I'm darned if I can find the valeo part number, I have it somewhere, I'll keep looking.
There are at least 2 different versions of the HEVAC, early one's controlled the aircon compressor direct, later ones via a relay, fit an early one to a late car and it will show the book as the current drawn by the relay is insufficient to tell the ECU that the compressor is working. Fit a late one to an early car and it may fry the compressor drive circuit.