Thread: Strange HEVAC issue with MY 09/1995 P38 Range Rover

Definitely sounds like the blend motors need changing, at least the distribution and the RHS blend one. Most on here have experience of doing the change and new ones are generally recommended. There are several different ways of tackling the problem and I bet a few could now do the job in half a day. It does involve the partial disassembly of the dash. To avoid taking out the whole dash, involves cutting the plastic ductwork. Pretty sure the rangerover.net website instructions were the ones I followed.

I'll try to post the link to the instructions.

"RANGE ROVER BLEND MOTOR REPAIR ON A P38 a how to guide"
Just put this search in at rangeovernet and you will see a step by step guide on the blend motor replacement. And as said by davodsonsm I would suggest new replacements.......It is a lot easier to follow than trying to explain in one post.........good luck and welcome!

Hi there.
It defiantly sounds like the blend motors aren't doing what they should do.
One other thing to think about may be the flap is stuck. This is quite common too. The lack of air could be the direction flap stuck between them all, and therefore the volume of air is coming out, just in all directions. You may even find that it has a cut duct and is just blasting out the air behind the dash. The temperature control could also be a sticky flap. I would strongly recommend getting yourself a nanocom or similar to pin point the fault first. I have managed to remove the rhs blend temp motor with out cutting, or removing the duct, but in all fairness, it was a struggle, and my temper was getting very thin within half hour. To get the blend motors to move, you force them power from the back of the hevac unit, you need to partially remove the center console stuff so you can then undo the 4 screws holding the hevac in, then you can unclip the wires, and then put power to them. You'll also need to work out which wires to do. My fault at the moment is that the potentiometer is not working, so the car does not know where the flap is sitting.
Good luck with it, you will find it testing!

Hi Dave...and welcome to the forum I am sure you will be well supported...you have done your homework and sussed out quite a lot! Most impressed with your fuse box efforts...(we like that!! )

There's another well known issue with the (plastic) heater plenum "box"...it can become distorted due to high summer cabin temps. This can cause the moving flaps to bind thereby straining the blend motors and causing them to seize. Hence the $Book mark. The sudden increase in air flow after the "bump" may well have been caused by a flap being jolted past its 'seize' point...

would be well worth your while also checking the status of the pollen filters. There's a heap of info on these in rangerovers.net. This is a 5 minute job. clogged pollen filters also are responsible for fans working overtime...

Good luck with it.. keep asking questions!

Thanks very much guys. Great support!

I have been considering looking into some sort of diagnostic tool to try and help identify the source. Would one of these tools (black box?) help?

There seems tone a number of generic odbII diagnostic tools around, but from what I can tell the vehicle must be odbII compliant. I can't seem to find any documentation confirming if a 4.6 petrol 1995 p38 is compliant or not.

Would you guys recommend sourcing one of these tools?. If so, which would be a good cost effective option allowing me to read and clear codes?

Thanks again.

Dave

Dave

Welcome aboard. With respect to diagnostics, I have the Bluetooth Torque Pro app on my Android phone, it is easy to use but is limited in what it can read with respect to p38 specific information eg EAS. I also have the Faultmate FCR (Fault Code Reader) this useful little device lives in my centre console. It will read any faults and let you know what they are plus you can also clear the faults. What it does not do however is let you adjust any of the parameters. In hindsight, I wish I had paid the extra money for the next model that also lets you recalibrate and access the testing modes. A diagnostic tool that is only fairly new to the market is the RSW Solutions software. The RSW EAS software has been around now for quite some time and is widely available in its early incarnation as a free download. You will however require a laptop and a dedicated OBD2 interface cable. The new version gets access to a lot more of the p38 specific codes. I'm pretty sure there is someone on this forum with the latest RSW diagnostic software that may be able to give a first hand update on how well it performs.

Gary

Thanks very much Gary. Are you sure the RSW Software is compatible with the P38?. I had a read of their website and it doesn't seem to specify that it does (unless of course im missing it).


Back on the topic of my blend motors, I did a little more mucking around this afternoon, and I wonder if I've misdiagnosed some of it.


On further investigation, when I press the different buttons to redirect the air, it does seem to work, however it seems to be quite slow. IE: If it is coming out on the face, and I swap it to windscreen, it will take about 4-5 seconds to actually swap the air. Im used to modern cars doing it almost instantly, so im wondering if I am just expecting it to be quicker than it actually is? Does this time sound about right?


I think perhaps I was getting a little mislead by the fact that the air volume seems to be very low (I assume because the drivers side blower fan is not working.)


So....my task list so far is this (in relative order of ease)


For Blend Motors:
1) Disconnect the HEVAC plugs on the rear of the controller to clear the Book and exclamation mark to see if the motors start working (or if the book just comes straight back)
2) Pull out the HEVAC controller and try to connect power to the blend motors independantly to see if they work.
3) Inspect the flaps to see if they are stuck. (I assume this requires some dash removal)?
4) Dependant on above tests - begin replacing blend motors.


For the Drivers Side Blower Fan
1) Ill admit im a littl estmped for ideas on this one - with the exception of standard troubleshooting / pulling it out and just inspecting / replacing it. Any other helpful pointers?


Thanks all - what a great community.


Dave

Dave

Specifically for a p38

EAS Unlock V3

Storey Wilson (the software developer) has a p38 as his own car

Gary