Rover 75 Con SE 2.0 CDTi - Radiator Cooling Fan Always On

cashford · 21st March 2024, 14:39

Hi All

I know there have been many posts on this in the past but most seem a long time ago so I thought I'd ask what might be the same question again as the 'fix' options might be different now.

In the last few days the radiator fan has starting coming on just a second or two after switching on the ignition (engine does not need to be on) and remaining on the whole time the car is running before finally stopping about 5-10 seconds after the ignition is turned off.

Based on all the posts I have found I have done ... listed below, I think it's probable something to do with PCB or relays mounted in the side of the radiator fan housing.

I have not had the front off the car yet, but from peering through the grille it seems my radiator does NOT have a resistor on it.

The tests/checks I have done are:

1. Air con off and in Econ mode.. Fan stays on. Air con/Fan switched completely to off... Fan stays on. Front Demist switched on... Fan remains.... Basically no impact whatever I change there.

2. Fan seems to just come on irrespective of whether the engine is running or not but does stop shortly after the ignition is switched off.. From what I've read this seems to rule out a relay in the PCB module being stuck

3. Checked connections behind OSF headlight so signs of water ingress.

4. Checked the dashboard display diagnostics to check temperature is being read correctly by the sensor... starts off about 10 degrees (probably right of the weather now) and rises as the car is driven to about 90 ish

5. Temperature gauge on the dash also works as you would expect and ends up at the 9 O'Clock Position so probably not the Temperature sensor on the engine

6. Disconnected the Aircon Trinary switch to see if the fan stopped or sped up... no impact... just kept running

So based on the fact that there appears to be no resistor I think it must be the radiator fan PCB, or possibly (I think I have read) the PWM signal wire?

I guess my questions are simply this... I am no genius .. indeed all I have done to get this far is follow other posts on the forum so...

Do you guys who are far cleverer than me agree with my thoughts?
Do you have any other suggestions
Most importantly, if you do agree with me... Does anyone know how I can get the PCB repaired.... I see there have previously been some members that can help here but the posts were very old, so hence the reason for asking the questions afresh.

Thank you all so much.

CHARLES

21st March 2024, 14:39	#1
cashford Newbie Rover 75 Saloon Join Date: Nov 2023 Location: Bournemouth Posts: 19 Thanks: 0 Thanked 0 Times in 0 Posts	Rover 75 Con SE 2.0 CDTi - Radiator Cooling Fan Always On Hi All I know there have been many posts on this in the past but most seem a long time ago so I thought I'd ask what might be the same question again as the 'fix' options might be different now. In the last few days the radiator fan has starting coming on just a second or two after switching on the ignition (engine does not need to be on) and remaining on the whole time the car is running before finally stopping about 5-10 seconds after the ignition is turned off. Based on all the posts I have found I have done ... listed below, I think it's probable something to do with PCB or relays mounted in the side of the radiator fan housing. I have not had the front off the car yet, but from peering through the grille it seems my radiator does NOT have a resistor on it. The tests/checks I have done are: 1. Air con off and in Econ mode.. Fan stays on. Air con/Fan switched completely to off... Fan stays on. Front Demist switched on... Fan remains.... Basically no impact whatever I change there. 2. Fan seems to just come on irrespective of whether the engine is running or not but does stop shortly after the ignition is switched off.. From what I've read this seems to rule out a relay in the PCB module being stuck 3. Checked connections behind OSF headlight so signs of water ingress. 4. Checked the dashboard display diagnostics to check temperature is being read correctly by the sensor... starts off about 10 degrees (probably right of the weather now) and rises as the car is driven to about 90 ish 5. Temperature gauge on the dash also works as you would expect and ends up at the 9 O'Clock Position so probably not the Temperature sensor on the engine 6. Disconnected the Aircon Trinary switch to see if the fan stopped or sped up... no impact... just kept running So based on the fact that there appears to be no resistor I think it must be the radiator fan PCB, or possibly (I think I have read) the PWM signal wire? I guess my questions are simply this... I am no genius .. indeed all I have done to get this far is follow other posts on the forum so... Do you guys who are far cleverer than me agree with my thoughts? Do you have any other suggestions Most importantly, if you do agree with me... Does anyone know how I can get the PCB repaired.... I see there have previously been some members that can help here but the posts were very old, so hence the reason for asking the questions afresh. Thank you all so much. CHARLES