75 V6 2.0 (2000) ATC query

Filch · 24th November 2007, 10:43

Hi all,

Hopefully someone can help! Have been through all the posts re: fan problems with the ATC, and almost all seem to reference the big radiator fan. My problem seems to be slightly different...

Firstly, the 3-speed radiator fan works fine. I've checked it by looking through the grill, and it goes slow, speeds up when you turn on the ATC and slows back down etc when you turn ATC off. So, I'm assuming it's ok - it acts as it's supposed to according to the posts, anyway. Engine temp never goes up and all seems good.

The problem I'm having seems to be with the internal? fans. I've run the diagnostic on the ATC and it gives FC 00 so all appears ok with the unit. However, the system doesn't actually blow any air into the cabin until a random time between 10 and 20 minutes. It'll just suddenly come on. Best way of describing it is - if you start the car and turn on the demister - there's nothing coming out of any vents. After a while...it'll come on and be blasting away merrily as if nothing's wrong.

Once it's working - the system seems fine...cold/hot and ATC functions as it's supposed to. No 30-sec on/off things...once going, it's great.

I took it to the local evil KwikFit today for a regas since it's been over 3 years , and they wouldn't touch it because the blowers weren't operating. They advised me to take it to a Rover dealer who'd have to remove the entire dash and replace the internal fan motors which were probably seizing.

Any advice? Fingers are firmly crossed!

Cheers!

Filch · 24th November 2007, 11:53

Thanks for the response!

It doesn't seem to matter what temp it's set to, either Lo to Hi with all in between. The blowers don't blow anything at all until it decides to start, then they're fine. I'm pretty sure it doesn't matter if the ATC unit is set to LO - they still won't blow for between 10-20mins

It'll happen when the engine's warmed up, and when starting from cold too - doesn't seem to be affected. Once the car is warmed up though, it can take as little as 5 mins until they'll kick in, rather than 10-20.

Hope that helped...

JohnDotCom · 24th November 2007, 12:01

The Internal fans won't work properly till car is up to Temperature normally.
A suggestion of Mike's that often helps, press the Window De-mist button, does this bring the Fans on at full speed or not?

Filch · 24th November 2007, 12:09

Unfortunately, hitting the de-mist button doesn't work. Until the system decides it wants to work, the fans don't work at all - including on demist. You can actually hear the main fan at the front kick up to a higher speed, but the internal blowers don't react.

Irritatingly, once it's actually decided to work - the system works flawlessly. Then de-mist brings the fans on at full speed, and the ATC functions normally.

It's almost as though the blower fans are 'stuck' until some time passes, then they free up and the system works. This seems unrelated to the ATC unit/computer and the main radiator fan.

Sorry!

JohnDotCom · 24th November 2007, 15:12

As you suspected then definitely a Fault with heater matrix Fan or Controller.
That should always bring them on at full blast.
Perhaps Keith or someone has an Idea to help Please?

Keith · 24th November 2007, 15:56

Quote:

Originally Posted by JohnDotCom

Perhaps Keith or someone has an Idea to help Please?

Yes but it would involve sticking it on my machine to work out exactly what bits of the system are working as they should, as it sounds far to complex to start speculating on here

OP If you put the system to Econ do you have full manual control?

One thing to check as this has happened before pull out the ATC panel disconnect the black and white plug and examine the plugs for any pushed back sockets

Filch · 24th November 2007, 16:08

Thanks so much to all posters for their help & advice.

Unfortunately, hitting ECON doesn't make any difference, either manually adjusting the fan speed or just allowing ECON to act auto without the AC - until the system starts working and then it does just what it should.

I'll certainly try removing the ATC unit and checking the plug at the back. If that's not the case though - looks like it'll be into a dealer and most likely £££ pain.

Really appreciate your time & views.

Cheers!

Departed · 24th November 2007, 17:43

Could be the motor or the controller, or maybe even the feed to the motor.

I'd start by checking the fuse is tight and no corrosion.

If it's the motor then it would be brushes to be intermittent, but usually these work to start with then stop when they get hot.

To check the controller itself, see if you can borrow one. They are easy to change over, and a bad soldered joint on the boaqrd might give the symptoms you have without any fault codes.

For the feeds,just check wires and connectors as much as you can.

The behaviour that you describe could be down to the unit thinking the engine is cold, hence everyone asking about when it happens. However, if you switch on front demist, this overrides the 'keeping the speed low until the engine is warm' strategy, hence itt's not that.

Hope it helps a bit.

Keith · 24th November 2007, 17:52

I assume the temp shown on the instrument cluster is ok not at -30?

Filch · 24th November 2007, 20:45

Thanks Lowedb - will try to get the ATC unit out tomorrow & check everything as recommended so far. Hopefully it'll be a loose wire or something simple!!

Keith - quite right in your assumption: the temp on the cluster is accurate for outside...cold just now, but not that cold

24th November 2007, 10:43	#1
Filch Newbie Rover 75 Saloon Join Date: Mar 2007 Location: Bristol Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	75 V6 2.0 (2000) ATC query Hi all, Hopefully someone can help! Have been through all the posts re: fan problems with the ATC, and almost all seem to reference the big radiator fan. My problem seems to be slightly different... Firstly, the 3-speed radiator fan works fine. I've checked it by looking through the grill, and it goes slow, speeds up when you turn on the ATC and slows back down etc when you turn ATC off. So, I'm assuming it's ok - it acts as it's supposed to according to the posts, anyway. Engine temp never goes up and all seems good. The problem I'm having seems to be with the internal? fans. I've run the diagnostic on the ATC and it gives FC 00 so all appears ok with the unit. However, the system doesn't actually blow any air into the cabin until a random time between 10 and 20 minutes. It'll just suddenly come on. Best way of describing it is - if you start the car and turn on the demister - there's nothing coming out of any vents. After a while...it'll come on and be blasting away merrily as if nothing's wrong. Once it's working - the system seems fine...cold/hot and ATC functions as it's supposed to. No 30-sec on/off things...once going, it's great. I took it to the local evil KwikFit today for a regas since it's been over 3 years , and they wouldn't touch it because the blowers weren't operating. They advised me to take it to a Rover dealer who'd have to remove the entire dash and replace the internal fan motors which were probably seizing. Any advice? Fingers are firmly crossed! Cheers!

24th November 2007, 11:53	#2
Filch Newbie Rover 75 Saloon Join Date: Mar 2007 Location: Bristol Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks for the response! It doesn't seem to matter what temp it's set to, either Lo to Hi with all in between. The blowers don't blow anything at all until it decides to start, then they're fine. I'm pretty sure it doesn't matter if the ATC unit is set to LO - they still won't blow for between 10-20mins It'll happen when the engine's warmed up, and when starting from cold too - doesn't seem to be affected. Once the car is warmed up though, it can take as little as 5 mins until they'll kick in, rather than 10-20. Hope that helped...

24th November 2007, 12:01	#3
JohnDotCom * Rover 75 FaceLift Tourer CDTi 170BHP Auto ConnSE 2005 Model Starlight Silver Join Date: Nov 2006 Location: Abergele Posts: 28,735 Thanks: 0 Thanked 6 Times in 5 Posts	The Internal fans won't work properly till car is up to Temperature normally. A suggestion of Mike's that often helps, press the Window De-mist button, does this bring the Fans on at full speed or not?

24th November 2007, 12:09	#4
Filch Newbie Rover 75 Saloon Join Date: Mar 2007 Location: Bristol Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	Unfortunately, hitting the de-mist button doesn't work. Until the system decides it wants to work, the fans don't work at all - including on demist. You can actually hear the main fan at the front kick up to a higher speed, but the internal blowers don't react. Irritatingly, once it's actually decided to work - the system works flawlessly. Then de-mist brings the fans on at full speed, and the ATC functions normally. It's almost as though the blower fans are 'stuck' until some time passes, then they free up and the system works. This seems unrelated to the ATC unit/computer and the main radiator fan. Sorry!

24th November 2007, 15:12	#5
JohnDotCom * Rover 75 FaceLift Tourer CDTi 170BHP Auto ConnSE 2005 Model Starlight Silver Join Date: Nov 2006 Location: Abergele Posts: 28,735 Thanks: 0 Thanked 6 Times in 5 Posts	As you suspected then definitely a Fault with heater matrix Fan or Controller. That should always bring them on at full blast. Perhaps Keith or someone has an Idea to help Please?

24th November 2007, 16:08	#7
Filch Newbie Rover 75 Saloon Join Date: Mar 2007 Location: Bristol Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks so much to all posters for their help & advice. Unfortunately, hitting ECON doesn't make any difference, either manually adjusting the fan speed or just allowing ECON to act auto without the AC - until the system starts working and then it does just what it should. I'll certainly try removing the ATC unit and checking the plug at the back. If that's not the case though - looks like it'll be into a dealer and most likely £££ pain. Really appreciate your time & views. Cheers!

24th November 2007, 17:43	#8
Departed Retired -- Join Date: Jan 2007 Location: -- Posts: 3,785 Thanks: 0 Thanked 4 Times in 4 Posts	Could be the motor or the controller, or maybe even the feed to the motor. I'd start by checking the fuse is tight and no corrosion. If it's the motor then it would be brushes to be intermittent, but usually these work to start with then stop when they get hot. To check the controller itself, see if you can borrow one. They are easy to change over, and a bad soldered joint on the boaqrd might give the symptoms you have without any fault codes. For the feeds,just check wires and connectors as much as you can. The behaviour that you describe could be down to the unit thinking the engine is cold, hence everyone asking about when it happens. However, if you switch on front demist, this overrides the 'keeping the speed low until the engine is warm' strategy, hence itt's not that. Hope it helps a bit.

24th November 2007, 17:52	#9
Keith This is my second home ZT400 Join Date: Oct 2006 Location: Ellesmere Posts: 5,948 Thanks: 0 Thanked 43 Times in 29 Posts	I assume the temp shown on the instrument cluster is ok not at -30?

24th November 2007, 20:45	#10
Filch Newbie Rover 75 Saloon Join Date: Mar 2007 Location: Bristol Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks Lowedb - will try to get the ATC unit out tomorrow & check everything as recommended so far. Hopefully it'll be a loose wire or something simple!! Keith - quite right in your assumption: the temp on the cluster is accurate for outside...cold just now, but not that cold