Heating/Aircon - Drivers Blower Motor Permenantly On

Hi All

Range Rover P38 Year 2000 (X) 4.6L Petrol/LPG

My apologies for starting a new thread! Previously (Heater/Air con Permanently stuck on!) I have a more accurate description of the problem!

The drivers blower motor is permanently stuck on.

I have had the car put on a test book and the following 3 faults are recorded:
1. Driver Blower Motor circuit fault (Stop Mode)
2. Driver Blower motor circuit fault (Regulation Mode)
3. Heater Core Temp. Sensor circuit fault (S/C to 0v)

My questions are:

1. Do the faults indicated, indicate a specific fault?
2. Heater Core Temp sensor - which one is it? A part No would be helpful!
3. What does S/C to 0v mean?

Any help or advice would be greatly appreciated.

Thanks

Bison

Would be a great help if you expanded on your post.
What model and year is it?????
My Crystal ball, like my memory is seriously clouded.

:beer2::beer2::beer2:

Doh!

Range Rover P38 Year 2000 (X) 4.6L Petrol/LPG

I am a dipstic! I was concentrating more on puting the detail in!

Thanks Irish Rover.

Regards

Bison

Bison said:

Hi All

Range Rover P38 Year 2000 (X) 4.6L Petrol/LPG

My apologies for starting a new thread! Previously (Heater/Air con Permanently stuck on!) I have a more accurate description of the problem!

The drivers blower motor is permanently stuck on.

I have had the car put on a test book and the following 3 faults are recorded:
1. Driver Blower Motor circuit fault (Stop Mode)
2. Driver Blower motor circuit fault (Regulation Mode)
3. Heater Core Temp. Sensor circuit fault (S/C to 0v)

My questions are:

1. Do the faults indicated, indicate a specific fault?
2. Heater Core Temp sensor - which one is it? A part No would be helpful!
3. What does S/C to 0v mean?

Any help or advice would be greatly appreciated.

Thanks

Bison

Click to expand...

3. What does S/C to 0v mean? It means a short circuit to zero volts i.e. the metalwork of the body/battery negative. Sounds like you have a wire chaffed through or maybe the sensor has failed in a mode that produces a short circuit. Anyway the sensor would be my starting point.

Irishrover said:

Would be a great help if you expanded on your post.
What model and year is it?????
My Crystal ball, like my memory is seriously clouded.

:beer2::beer2::beer2:

Click to expand...

Or is it cloudy beer

Right On Datatek......It's me age and the addled brain !!!!!

:hysterically_laughi

Thanks Guys

My 1st action would have been to change the sensor. Sound advice me thinks! Best I order a sensor. I now know what S/C stands for too. Brilliant!

Thanks again

Bison

Hi all

Well I changed the Heater Core Temp sensor (STC3256) but that has not solved the problem. I was never going to be that lucky! Did I change the right one according to the diagnostics?

Im guessing the chaffed or broken wire is the way of investigation.

Does anyone have any advice?

Thanks all

Bison

The sensor is clipped onto the metal pipe just before the heater core. Did you have the fault cleared AFTER fitting the new one ?

Hi rewmer

Yes that is the sensor I changed. So thats good news.
You also ask an excellent question "Did you have the fault cleared AFTER fitting the new one ?" My answer is no! I'm guessing my next move is to see if they can clear the fault! I didn't realise that the fault had to be cleared. Once again I learn something that is useful. Thank you.

Bison

Hi all

have taken my car to MDP to clear the faults on the test book. Core temperature sensor is now fixed.

However, the following faults remain:
1. Driver Blower Motor circuit fault (Stop Mode)
2. Driver Blower motor circuit fault (Regulation Mode)

Description of operation from “RAVE”

Battery voltage is supplied to the positive side of the
blower motors via the auxiliary relays. Blower speed is
controlled by regulating the voltage of blower control
signals from the ATC ECU to the negative side of the
blower motors. When the blower control signals are
equal to battery voltage, the blowers are stopped.
Reducing the voltage of the blower control signals
increases blower speed until, when the signals are
earthed, the blowers are at maximum speed.

I have carried out continuity testing an all wiring from the blower motor to the HEVAC to the fuse box and their respective earths and all seems to be ok.

I have done some voltage comparisons from one side to the other and most voltages appear normal. I am not sure about the feed back voltages because they fluctuate!

I have slaves a second hand HEVAC (Appears to be in working order!) in no change the blower motor keeps running at max.

I have made my own loom and connected the right hand side blower motor connector the left hand side blower motor, no change the blower motor keeps running at max.

I have slaved a second hand blower motor into the left hand side however that didn’t work at all even when I slaved it into the right hand side!

I am currently awaiting another blower motor.

In the meantime has anyone got any other ideas?

Thanks and regards

Bison

Have you pulled the Blower relays (RL6 & 7) from out of the Engine bay fusebox?
They are the two front yellow ones in the row of yellow relays running parallel to the wing. Are there signs of scorching either around the relay pins or the circuit board, this is a common fault on P38's.
To check easily, swap the relays with any of the other yellow relays of the same size/shape in the fusebox.

Hi Irishrover

Yes I have swapped the relays around and checked all the fuses and they are all fine. It was one of the first things I did.

Thanks

Bison

Hi all

Well, after the extensive electrical checks I replaced the blower motor with one from ebay. Despite being led around the houses by a mixture of faulty replacements and my relative lack of knowledge of the system, hey presto, it works.

It appears that the blower mortor was at fault.

Hope this helps

Bison