Blend motor doing funny things!!!

[redandy3575]

2 months ago i got the textbook symbol with the exclamation mark, i then thought ' here we go' time to rip into the dash again to fix the driver side blend motor. I wasn't paying any attention to the HEVAC as i don't have the spare funds at the moment to buy a new blend motor. So i was planning on leaving this repair (seeing that it's not urgent) to later this year. I looked at the Hevac today and noticed the textbook exclamation symbol gone and the blend motor working again.....'what the'. After doing all the test before and checking the fuses, i was convinced the blend motor was gone, but seemed to have fixed itself. I'm guessing that it may have been stuck shut or something. Has anyone else had this happen???

[98se40]

Hi RedAndy,

yep, is happening to me on a regular basis.....plug in a Faultmate and it tells me I have a short in the drivers side blend motor, hence the textbook symbol.
Maybe 3 days later, the textbook symbol is gone,......Im like you, once the money tree grows more, Im getting all blends done........but at the moment, nothing urgent.
Cheers

[RR P38]

It is common for older units to be stuck and then move as you bump your way along a road.
Its just an indication that it is on its way out?
If you run your HEVAC on manual now that you have the problem resolved in the short term you can put off the repairs for a while.
Through test book it is possible to cycle the blend motors and test their function, this also fully opens and closes them and can clear up any logged faults.
Have you cleaned out your plenum filters(x2)?

[Hoges]

FWIW I have similar issue and have noticed that the symbol only appears when the car is left standing and the outside temp exceeds about 15degC. Or it's been parked in the sun on a chilly day but absorbs heat because of its colour (Java black).

Confirmed this on Monday: The other night driving home from Sydney the book symbol was on and the passenger side got only cold air :mad: Stopped at Sth. Grafton about 1.00 am for about an hour for "food " ...temp outside was 4 degC.

Time to go: turned ignition key to position 2 and heard heater flaps creaking into place, book symbol had disappeared!:eek: Started engine: warm air all around, everybody HAPPY :D

Verdict: Not the blend motor but rather a sticking flap due to slight distortion of the plenum due to external temp, causes flaps to jam due to tight tolerances: therefore blend motor can't operate flap to fullest travel---> book symbol!

Before parting with $$$$ check flap travel;)

Now exploring how might get a Dremel with flex drive into said space and grind out a few thou. to free up tolerances for flap to move freely... spraying with WD40 etc only causes other issues and besides it's not great to be inhaling it in a confined space...

[RR P38]

When you hear that creaking noise it is actually the air intake flaps that are under your intake filters. If you pull the filters out and look inside with a torch, flick ignition on/off and you will see them open and close.
They close automatically every time you shut down your ignition/stops air from getting into the cab? Not sure why you would want to do this?

[redandy3575]

When you hear that creaking noise it is actually the air intake flaps that are under your intake filters. If you pull the filters out and look inside with a torch, flick ignition on/off and you will see them open and close.
They close automatically every time you shut down your ignition/stops air from getting into the cab? Not sure why you would want to do this?

It's to preserve that Range Rover fragrance!!!!:D

[redandy3575]

It is common for older units to be stuck and then move as you bump your way along a road.
Its just an indication that it is on its way out?
If you run your HEVAC on manual now that you have the problem resolved in the short term you can put off the repairs for a while.
Through test book it is possible to cycle the blend motors and test their function, this also fully opens and closes them and can clear up any logged faults.
Have you cleaned out your plenum filters(x2)?

I have about a year ago. Might have to do it again. I ahve had water leak in on the passenger side, might have to get a new cover as well.

[redandy3575]

Well almost 6 months has gone by and the situation is only getting worse. The 2 blower motors have decided to slowly call it quits, so now i've got nothing. The old blend motor on the driver side is still sitting dislodged behind the instrument cluster. I have checked everything out and (without a proper diagnostic) reckon it might be the external fuse box, which is badly burned around the ( no points for guessing ) Relay 7, as the fans graduely stopped working. So a newer fuse box is on the cards. The new blend motor will be installed next week.

[Hoges]

Well almost 6 months has gone by and the situation is only getting worse. The 2 blower motors have decided to slowly call it quits, so now i've got nothing. The old blend motor on the driver side is still sitting dislodged behind the instrument cluster. I have checked everything out and (without a proper diagnostic) reckon it might be the external fuse box, which ihttp://www.rangerovers.net/repairdetails/electrical/fusebox.htmls badly burned around the ( no points for guessing ) Relay 7, as the fans graduely stopped working. So a newer fuse box is on the cards. The new blend motor will be installed next week.

Blend Motor Diagnosis and Replacement (http://www.rangerovers.net/repairdetails/blendmotor.html)
Fuse Box Repairs (http://www.rangerovers.net/repairdetails/electrical/fusebox.html)

[RR P38]

Well almost 6 months has gone by and the situation is only getting worse. The 2 blower motors have decided to slowly call it quits, so now i've got nothing. The old blend motor on the driver side is still sitting dislodged behind the instrument cluster. I have checked everything out and (without a proper diagnostic) reckon it might be the external fuse box, which is badly burned around the ( no points for guessing ) Relay 7, as the fans graduely stopped working. So a newer fuse box is on the cards. The new blend motor will be installed next week.

If you dont want to buy a new fuse box $$$. You can actually repair it.
With the heat the relay pin receivers de solder and drop out.
If you have a decent sized soldering iron its not that hard to fix.
Araldite can be used to secure the receivers in place.
The whole thing is seriously heavy duty copper and well repairable.
I repaired mine about 6 years ago and have had no further problems.
The only evidence of a repair is a slight crack and some Araldite under the relay which is not visible with the relay in place.

[brucep]

Hi,

I had similar issues with blend motors.....someone on here posted a link to this guys page (See Below), and it is very helpful. I replaced the pots in my motors, and they are fine again now. (I also purchased new ones, before I read about fixing them). The pot (potentiometer) is what provides feedback to the Hevac ECU on the postion of the motor.....the carbon track wears away, and the feedback resistance goes all over the place.

Range Rover P38 Maintenance repair improvements and tips learned by experience by ownership. (http://www.stockholmviews.com/p38/index.html#blend)


I have got heaps (50) of replacement pots to suit these if you need any......I'd happily post some to you for nothing if you want to give the repair a go.

Hope that is of some help.

Regards,

Bruce

[redandy3575]

If you dont want to buy a new fuse box $$$. You can actually repair it.
With the heat the relay pin receivers de solder and drop out.
If you have a decent sized soldering iron its not that hard to fix.
Araldite can be used to secure the receivers in place.
The whole thing is seriously heavy duty copper and well repairable.
I repaired mine about 6 years ago and have had no further problems.
The only evidence of a repair is a slight crack and some Araldite under the relay which is not visible with the relay in place.

I managed to source a good second hand fuse board for around $100 From the UK. I installed it today and guess what.......the blowers are working again....yeay... But the blend motor remains to be fixed. I still have the old board, and might have a crack at repairing it in the future as spare.

[glenhendry]

Hi,
I had similar issues with blend motors.....someone on here posted a link to this guys page (See Below), and it is very helpful. I replaced the pots in my motors, and they are fine again now. (I also purchased new ones, before I read about fixing them). The pot (potentiometer) is what provides feedback to the Hevac ECU on the postion of the motor.....the carbon track wears away, and the feedback resistance goes all over the place.

Range Rover P38 Maintenance repair improvements and tips learned by experience by ownership. (http://www.stockholmviews.com/p38/index.html#blend)


I have got heaps (50) of replacement pots to suit these if you need any......I'd happily post some to you for nothing if you want to give the repair a go.

Hope that is of some help.
Regards,
Bruce

Excellent input! I suspect the same thing for my temp blend motors. I would love to give that fix a go, as the most difficult part about replacing the blend motors is the routing of the cables from what I can see as a opened the dash to do the job.

Where you able to get the pots using the same part numbers as in the stockholm views site or are the aussie suppliers different?

Thanks!

[brucep]

Hi,


Yes, the Piher PT15NV-10k is the part number. I had trouble getting any locally, but found Rockby Electronics had the same trimpot, but with a thumbwheel pushed on.....it is very easy to press the thumbwheel off - it's just a manufacturing option on the standard PT15NV pot. They are 30 cents each - you must buy min 10 pcs.....a very expensive fix!! Here is a link:

Results Page (http://www.rockby.com.au/catresults.cfm'select=19&subcode=154&offset=41&stock_no=28271)

Regards,

Bruce

[redandy3575]

Blend motor all fixed. Have Air conditining again.........y:Deah!!

[poleonpom]

Hi,

I had similar issues with blend motors.....someone on here posted a link to this guys page (See Below), and it is very helpful. I replaced the pots in my motors, and they are fine again now. (I also purchased new ones, before I read about fixing them). The pot (potentiometer) is what provides feedback to the Hevac ECU on the postion of the motor.....the carbon track wears away, and the feedback resistance goes all over the place.

Range Rover P38 Maintenance repair improvements and tips learned by experience by ownership. (http://www.stockholmviews.com/p38/index.html#blend)


I have got heaps (50) of replacement pots to suit these if you need any......I'd happily post some to you for nothing if you want to give the repair a go.

Hope that is of some help.

Regards,

Bruce

Bruce, that's a great reference site; I've been looking for info on the blend motors as I'm planning to 'have a go'

Where did you source the replacement pots?

Jonathan

[brucep]

Hi,

I got them from Rockby Electronics. If you PM me an address I'll be happy to post some to you.

Regards,

Bruce

[glenhendry]

You can test the operation of the pot on the blend motor assembly. You put the black multimeter probe on the top leg and the red on one of the other two legs. When the pot's wheel is turned the pot should vary the resistance from between 0 to about 10.5. This is as tested on a new pot and also the pot installed on my (not working) blend motor. When you switch the red probe to the other leg, the figures are the same in reverse. Presumably if the carbon track was worn you would get some other reading.

Bruce kindly send me some pots, but since I noticed this before I installed them in the blend motors, I figured that it wasnt the pots that was causing mine to fail so I continued and replaced all three blend motors. I have hot air now (and cold) but the !book symbol remains.