heater blower fans got mind of thier own!!!

v8p38 · Apr 19, 2011

A bit puzzled here

On my P38, I turn ignition on and a few seconds later the blowers on the heater start blowing quite fast, try to turn it down and nothing happens, turn up the speed and it sounds like another set of blowers start, turn down the speed and it just stays the same as it did when it first came on.

If I adjust the temp it gets hot and cold and all the different vent settings seem to work as well, but I cant turn off the blower.

If I turn off ignition it may reset, but ignition back on, it kicks in again a minute later :doh:

Whats happenening I don't know where to look first

ladyranger · Apr 19, 2011

mine does something similar, it switches to program, front blowers, rear window heater and recycle air...all by its self!!! worse in damp weather so i've put it down moisture. it's querky, and freaks out the mechanic when it comes to MOT time

roddy4 · Apr 19, 2011

mine is a dodgy fusebox,yours could be the same?

Datatek · Apr 19, 2011

Check the underbonnet fuse box for signs/smells of burning, but it could be the HEVAC unit. Need the get the codes read.

v8p38 · Apr 19, 2011

Datatek said:
it could be the HEVAC unit. Need the get the codes read.

Do I need specialist diagnostic kits for this??

Forgot to mention That I have the handbook and ! showing on Hevac but it's been there since I bought the car months ago, just thought A/C needed regassing to reset that symbol :doh:
Obviously I am wrong on that point

Datatek · Apr 20, 2011

v8p38 said:
Do I need specialist diagnostic kits for this??

Forgot to mention That I have the handbook and ! showing on Hevac but it's been there since I bought the car months ago, just thought A/C needed regassing to reset that symbol :doh:
Obviously I am wrong on that point

There was no book symbol on mine when the aircon needed regassing, but I think that depends on model year. Look at the 2 blower relays in the under bonnet fuse box and check for signs of heating or burning, blued contacts etc. However if you have the book symbol it may well be the HEVAC ECU, so you need someone with a Faultmate or an indie with Autologic or Testbook to read the fault codes

v8p38 · Apr 20, 2011

Datatek said:
Look at the 2 blower relays in the under bonnet fuse box and check for signs of heating or burning, blued contacts etc. However if you have the book symbol it may well be the HEVAC ECU, so you need someone with a Faultmate or an indie with Autologic or Testbook to read the fault codes

Thanks Datatek.
I looked at relays this morning and one of them had brown burn marks on but fusebox seems to be ok. Bought a new relay and popped it in and it still done the same, blower fans come on by themselves :doh:

Maybe it is the fusebox or even worse the hevac.......hope it's not though

Datatek · Apr 20, 2011

If the relay is burnt, you can bet the fusebox is shot.

v8p38 · Apr 20, 2011

Just removed the fusebox and looked at connections underneath and all seems to be good, No signs of melting or burning

But fans still coming on, do you think I need a new hevac unit?

I know they are easy to replace but it's the cost of them

Or better still, Is there anyone in Merseyside who has a diagnostic kit who would be kind enough to check it out for me?

Datatek · Apr 20, 2011

The fuse box is a sandwich of 2 circuit boards, it fails on the solder joints on the PCB's, you will not easily see the problem from underneath, however as you have the book symbol it's just as likely to be the HEVAC.

v8p38 · Apr 20, 2011

Thanks Data,
I will probably change the fusebox and go from there

v8p38 · Apr 21, 2011

Well I changed the fuse box today and the left fan is still coming on constantly

Does this mean my hevac unit is Kerput?????

dogsbody · Apr 21, 2011

Try swapping the two relays over and see if the fault moves with the relay. The other relay could be FUBARed internally without showing any external marks.

stefanw · Apr 22, 2011

Usually it's a shorted out transistor inside the fan itself, quite easy to repair, the part is about ~£4-5.

I just finished repairing my left side fan the other day.

RangeRovers.net • View topic - blower motor repair

AP90 · Jan 8, 2015

Just whipped out the right hand blower motor which was running full tilt with a view to fitting new transistors.

However there is plenty of resistance across the 2 transistors and they are not shorting to the case, any of you clever chaps know if I should carry on with the replacement. or is there another cause for this? Relay??

The left hand motor runs fine and responds to input controls.

wammers · Jan 8, 2015

AP90 said:
Just whipped out the right hand blower motor which was running full tilt with a view to fitting new transistors.

However there is plenty of resistance across the 2 transistors and they are not shorting to the case, any of you clever chaps know if I should carry on with the replacement. or is there another cause for this? Relay??

The left hand motor runs fine and responds to input controls.

There should be a transistor that controls the fan speed big round thing i think. That maybe the problem. You can get a kit to replace it. http://www.ebay.co.uk/itm/Range-Rov...arts_Vehicles_CarParts_SM&hash=item4ae2c14d93

AP90 · Jan 8, 2015

wammers said:
There should be a transistor that controls the fan speed big round thing i think. That maybe the problem. You can get a kit to replace it. Range Rover P38 Mk2 Valeo heater blower fix kit. Replaces FW26025A1 | eBay

Thanks Wammers

Yes kit is on its way, just wondered, as the transistors have a good resistance reading across both of them.

I guess I'll just replace them and take it from there.

Thank you also for the "Island" link the other day.......can't see how I missed that, getting a few senior moments these days!!

tomcat59alan · Jan 8, 2015

Thank you also for the "Island" link the other day.......can't see how I missed that, getting a few senior moments these days!![/quote]

Join the club mate

Datatek · Jan 8, 2015

AP90 said:
Thanks Wammers

Yes kit is on its way, just wondered, as the transistors have a good resistance reading across both of them.

I guess I'll just replace them and take it from there.

Thank you also for the "Island" link the other day.......can't see how I missed that, getting a few senior moments these days!!

You can't just stick a meter across a transistor to test it, there are 3 connections, base, emitter and collector. Depending on type, the Emitter/collector junction should be open circuit with the meter leads one way round and show resistance or open circuit with the leads reversed. Base to Emitter or Collector should show resistance one way and a different resistance or open circuit with the leads reversed.
If the motor was in circuit when you tested, you would be reading the motor resistance.

tomcat59alan · Jan 8, 2015

Datatek said:
You can't just stick a meter across a transistor to test it, there are 3 connections, base, emitter and collector. Depending on type, the Emitter/collector junction should be open circuit with the meter leads one way round and show resistance or open circuit with the leads reversed. Base to Emitter or Collector should show resistance one way and a different resistance or open circuit with the leads reversed.
If the motor was in circuit when you tested, you would be reading the motor resistance.

The seller on ebay explains all that .

heater blower fans got mind of thier own!!!

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