'97, 2.5 DSE P38 heater fan fault

WayneRR4x4 said:

Ok, I may have solved the problem more simply, just found blowers for £15 each inc P&P, told them to send me two, I'll swap them, and then set about testing the crap out of the old ones in the comfort of my kitchen when I have time, if I find faults with transistors etc I'll buy new, refurb the units and sell them, even if I only break even it will be a win for me. Thanks for your help, I hope my continual posting about various things isn't too annoying, I'm just keen to do as much as possible myself, but got very limited knowledge.

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You do not annoy me and what you say sounds like a plan. Good luck.

wammers said:

Only one each side needs to be duff but you would not just change the duff one would you. Up to you, i can only say what it maybe. The relay is for high speed only, transitional speeds are controlled by the speed controller. So if the fans only work at high speed the relay will be fine, if they do not work properly on intermediate speeds the transistors will need looking at.

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And if they don't work at all, like mine?

WayneRR4x4 said:

And if they don't work at all, like mine?

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I take it you have looked at relays 6 and 7 in fuse box. Or did i miss that?

wammers said:

I take it you have looked at relays 6 and 7 in fuse box. Or did i miss that?

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Yup, taught myself how to use a multimeter, and then stripped, cleaned, and tested the relays, all good there, just had a heads up on the multi-plug for the main blower power feed located behind the kick-panel in the footwell, apparently these can get corroded and fail, looks like I'm going to be busy checking various bits on the weekend, well, I wanted to get more experience and knowledge... looks like its a crash-course in P38 maintenance!

Well, I think I'm out of my depth now.
Got access to the r/h blower, was going to take both out to test relay and transistors, but cant get the l/h one out as the glove box catch is knackered in some way, tried accessing the three screws as advised to get the glove box to open, and... it doesn't! So I cant access the l/h blower. Decided to check the power etc by probing the plug on the r/h blower, there's power, doesn't mean much but at least that's two possible fault options discarded (HVAC fault or multiplug fault), except... it could still be a HVAC fault as apparently the blower needs not just a power feed but also a "signal feed" from the HVAC... I would go and put my laptop on it and see what I find... but right now I'm worried that the sodding thing is jinxed and I'll crash my lappy, or find some horrendous faults.

I just purchased a replacement HEVAC control from Martyuk on here. Hoping to swap it over next few days (am going to mates garage to do the petrol tank...hopefully).

We think that because my car sat for 5 years & nothing was touched or moved or switched, that any crud on the buttons has dried on and created very poor connections.

I have seen e spinning the motor speed controller for weeks on end, but no adjustment happened. However, if I did it when I first went into the car I could dial up the speed I wanted with no issues and it held for as long as I was driving, then next day or next week, the speed was still there and the fans worked all the time.

I am waiting for George to flag up a major fault seeing as how it is built in to them. Shame the British motor industry has such a sh!te rep for reliability... Even a cartoon (Pixar Cars 2) has a famous line "You know what they say about ol' British engines, if there aint no oil under em' there aint no oil in em!" Sums it all up really. Doubly bad when the car is a beautifully designed Range Rover with all the luxury and good looks abound.

Mine worked sometimes, and then didn't, and now they don't work at all. I've got a couple of blowers coming (known workers), and I can access the one under the steering wheel, so I'll swap that one and see how it goes, if it doesn't work my next port of call is the HEVAC unit.

WayneRR4x4 said:

Mine worked sometimes, and then didn't, and now they don't work at all. I've got a couple of blowers coming (known workers), and I can access the one under the steering wheel, so I'll swap that one and see how it goes, if it doesn't work my next port of call is the HEVAC unit.

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For heating purposes the Hevac unit itself does not turn the fans up and down or on and off. That is done by the BECM subject to request signal from Hevac and subject to coolant temp. If half speed is dialed into Hevac the fans will only run at that speed when the coolant temp reaches a certain point. If full speed is dialed into Hevac fans will increase in speed subject to coolant temp and will not come on full until coolant reaches a certain level. The operation is automatic subject to coolant temp. The only time the fans will react almost instantly to different speed being dialed into the Hevac is when the coolant is at full temp. You may like to check that the temp sensor on the heater feed pipe under the dash is sound.

wammers said:

For heating purposes the Hevac unit itself does not turn the fans up and down or on and off. That is done by the BECM subject to request signal from Hevac and subject to coolant temp. If half speed is dialed into Hevac the fans will only run at that speed when the coolant temp reaches a certain point. If full speed is dialed into Hevac fans will increase in speed subject to coolant temp and will not come on full until coolant reaches a certain level. The operation is automatic subject to coolant temp. The only time the fans will react almost instantly to different speed being dialed into the Hevac is when the coolant is at full temp. You may like to check that the temp sensor on the heater feed pipe under the dash is sound.

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Oh boy, so... in summary, if the vehicle is cold (engine not running), or if its only just started, the fans wont come on despite me twiddling the fan speed knob... at least, until it gets warmer? I feel like a complete muppet now, so I should go out and run the engine for a while, see what happens? I'm a nugget... its official!

Surely they must sit at a low rotational speed as I'm sure I felt a little breeze when I fire up the engine!

So, would I be correct in assuming that since my little book and the ! only appear after driving for a bit, that there may be something additional awry with George?

Marty said my blenders may need a recoding (or similar) after I install the new HEVAC switching unit. I "know" it is faulty, but wonder if there are extra problems

Doo said:

Surely they must sit at a low rotational speed as I'm sure I felt a little breeze when I fire up the engine!

So, would I be correct in assuming that since my little book and the ! only appear after driving for a bit, that there may be something additional awry with George?

Marty said my blenders may need a recoding (or similar) after I install the new HEVAC switching unit. I "know" it is faulty, but wonder if there are extra problems

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Blend motors calibrate automatically but not very often. You can do it with a Nanocom. Book sign will more than likely be a blend motor sticking or a faulty pot. Diag would tell you. If fans are dialed off they will not come on at all. If they are set say to half speed, they may turn over slightly when engine starts but they will not go to half speed until coolant is warm enough. Try it with the programme setting and start from cold, fans will speed up progressively as coolant temp rises. At a certain temp they will go to full speed.

wammers said:

Blend motors calibrate automatically but not very often. You can do it with a Nanocom. Book sign will more than likely be a blend motor sticking or a faulty pot. Diag would tell you.

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Must be something, remembered that if I set, say, 20 degree's on the drivers side (passenger side always about 22) it's all fine until I speed up (from 30mph to 60mph) and the cabin slowly gets cooler, then I have to up to 21, then it's fine again, so I'm guessing that's when the book shows.

Doo said:

Must be something, remembered that if I set, say, 20 degree's on the drivers side (passenger side always about 22) it's all fine until I speed up (from 30mph to 60mph) and the cabin slowly gets cooler, then I have to up to 21, then it's fine again, so I'm guessing that's when the book shows.

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Blend motor then.

wammers said:

Blend motor then.

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Cheers Mr W. Whats best way to fix? I mean, replacement parts, etc. I have no problem going in to the guts of things...

Doo said:

Cheers Mr W. Whats best way to fix? I mean, replacement parts, etc. I have no problem going in to the guts of things...

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Blend motors can be repaired. Sometimes if diag indicates a short, you just need to clean the carbon dust from the armature. If a pot is gone, needs a new one soldering in. Think there are articles on RRnet how to repair them.

wammers said:

Blend motors can be repaired. Sometimes if diag indicates a short, you just need to clean the carbon dust from the armature. If a pot is gone, needs a new one soldering in. Think there are articles on RRnet how to repair them.

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I imagine something is sticking seeing how she sat on her arse for 5 years... Didn't help that the red herring was the HEVAC controller having duff buttons. Ahh well, better get me soldering iron oot

Doo said:

I imagine something is sticking seeing how she sat on her arse for 5 years... Didn't help that the red herring was the HEVAC controller having duff buttons. Ahh well, better get me soldering iron oot

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Change the Hevac and see what you get at least that is one possible trouble out of the way. I am betting on a blend motor. But without diag you can guess for the rest of the year.

wammers said:

Change the Hevac and see what you get at least that is one possible trouble out of the way. I am betting on a blend motor. But without diag you can guess for the rest of the year.

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When I first got George on the road, I took her to 4x4 specialist Hamish Grant, who interrogated her and no faults found. He said to come back later for another reading. I asked how much and he shook his head! I had the money in my hand too

Proper gentleman Hamish

I'll do the HEVAC and see if he can book me in to test the system, as Marty said it may need to be "told" what to do or words to that efect.

I'll let y'awl know the outcome

Thanks again

Doo said:

When I first got George on the road, I took her to 4x4 specialist Hamish Grant, who interrogated her and no faults found. He said to come back later for another reading. I asked how much and he shook his head! I had the money in my hand too

Proper gentleman Hamish

I'll do the HEVAC and see if he can book me in to test the system, as Marty said it may need to be "told" what to do or words to that efect.

I'll let y'awl know the outcome

Thanks again

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Depends what diag he has unless it's P38 specific he may not be able to do anything or be very limited.

wammers said:

Depends what diag he has unless it's P38 specific he may not be able to do anything or be very limited.

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It's a handheld thing like a massive fat tablet. Cost thousands. He's the go to guy for the local LR/RR dealership