blend motor

[blindin]

Hello again!
well after spending all weekend playing with the new to me p38, and newbie to p38's, I have to say, it has been the most frustrating weekend ever working on the car.
First up, I thought I would have a look at the cruise control, I got absolutely no where with it, I did how ever find out that I have power on the switch side, but no light, I got a little confused when I checked the high range, and low range, and got exactly the same voltage, not sure if the signal is supposed to be positive, or a ground signal. Any way, I know I will need new hoses, I thought they were ok, but on closer inspection, they look good, but are to big, so do not seal. Will have to come back to that another time.
So I also needed to look at the stereo, and while half of it was getting removed, I thought I would do the heater matrix. Long story short, heater now works, new hose and and o-rings, not sure how long it had been disconnected. How ever, after fighting the stupid air duct, and cutting the dash in half and twisting it half way through the car, it is now welded back, and back together, the stereo is back to original wiring, as the previous owner had done some weird wiring on it, I test it out, only to find that the hot is only on the passenger side.
I also checked the ac out, that to is now working, traced it to the clutch not engaging, I removed the shim, and it seems to be clicking in now, although it does click in and out a lot, not sure if thats right, but have only had it running a short time.
Today I have striped it down again, I wish I had done some reading first as there were probably a few short cuts I could've done.
I put direct voltage to the blend motor, and it works, so why would it not make any movement from the control?
I should've tested every thing again, but I didn't, I will tomorrow.
My question is......
If the blend motor works when I connect it to voltage, does this mean, the control unit is knackered?
Is there a test I can do?
Could it be the temp sensor on the heater hose?
I broke the clip, but have it securely cable tied on, can it be tested?
Also is any one good with repairing the plastics of the dash, I have found that all the plastic is broken, and there are very few screw which can be done up, the facia around the instrument cluster do not fit at all, as there are no screws holding it on, it may be due to twisting the dash that it does not fit, but it would still be nice to be able to secure it some how.
I am now also suffering with a flat battery, this happened before I touched any wiring, and the only thing was the stereo removed, so not sure whats happening there.
Any suggestions welcome
Thanks Simon

[PeterH]

The blend flaps can jam, which might explain the motors working but not moving. You would have to do a search here or on rangerovers.net for the fix.
Try some cable ties on the cruise control hoses where they connect, that should seal the vacuum without having to replace the hoses, (provided the hoses are good of course).
The temp sensor is a common failure item, I would replace it with a new one, they are not expensive.
Good luck with it all!

[Hoges]

check out Photos of method for freeing blend flaps with S/T Screw - Page 3 (http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/14322-photos-method-freeing-blend-flaps-s-t-screw-3.html) for some photos of the self tapping screw "fix" to relieve stress on the flap due to heat induced warping of the plenum...

[poleonpom]

Blend motors have potentiometer pots in them that wear out and therefore the whole unit will not work even though the motor tests Ok. Have a look at http://www.stockholmviews.com/p38/index.html#blend

[blindin]

Thanks for the replies.
The flap moves freely, well it does by hand, and I get variable reading from the resistor too.
I will today check to see if I apply voltage to it, if it has enough grunt to move the flap. ( I should've done this before I ripped it apart again )
What symptoms would I get from bad sensor? ( the one on the pipe )
Also, is there a way to set the gears, as the resistor has to match the position of the output shaft. As I have had it apart, I am unsure if it's right.

[Hoges]

See Blend Motor Diagnosis and Replacement (http://www.rangerovers.net/repairdetails/blendmotor.html) for pics of blend motor etc in partly disassembled state. I'm not sure the potentiometer positioning is critical because the ECU controlling the heating/cooling performs a 'calibration' when the ignition switch is turned on.

[TheTree]

nanocoms and similar units have a blend motor calibration function in them

Might be an idea to see if someone can do that for you once you get it back together

Steve

[ian4002000]

I had trouble with the face air vent being low flow, I was testing my nanocom on the p38 and found the calibrate flaps button. I pushed and all flaps moved and the flow was increased and working well since.
Just got to find why the P/s fresh air motor has stopped half way ?

[blindin]

Hi, well, check it all in the morning, and guess what?
All working fine. I think I may have the internal gears out one tooth on the blend motor as it isn't quiet as cold as the passenger side, but having said that, you would never notice if you didn't sit there comparing them together.
I have since put it back together, and again, removed the plastics around the dash to try and repair, but with out success. I tried the fibreglass matting stuff, but was just it horrendous, so any ideas welcome to repair, well form the missing pieces where the screws go.

[TheTree]

I have not really thought of a good way to fix those broken tabs

I believe Ron Beckett made a matching coloured glue by dissolving some shavings of ABS in Acetone.

We used to make a glue for AirFix kits by dissolving perspex in acetone, and sometimes just used the acetone straight on the bits as well.

Plumbers PVC cement also smells like it's acetone based.

An ebay search for "abs plastic repair kit" turns up some interesting things, including a welding gun, but that is an expensive option!

There is also this;

Plastic Repair KIT Plastex Custom Audio Install Tools ABS Plastic Repair | eBay (http://www.ebay.com.au/itm/Plastic-Repair-Kit-Plastex-Custom-Audio-Install-Tools-ABS-Plastic-Repair-/281382454474?pt=Car_Audio_Video&hash=item4183b384ca)

ACRI-BOND glue seems to work with ABS and you can also use a soldering iron

http://www.ehow.com/how_6581320_repair-cracked-abs-plastic.html

Good luck!

Steve

[blindin]

I saw this, but only sold in the u.s.
Plast-aid

[wayneg]

I did a write up on my efforts to renew the pots in the bend motors. It shows how to re-align the gears
See attached

[blindin]

I think I may have been lucky, I removed the gears, and turned it half way by eye. I did notice one of the gears had an arrow, and there was also a mark on the the resistor / potentiometer. Mine is working at the moment, and I've been very lucky to get it set up by eye.