Temp gauge @ 12:00 but aircon fans on a lot!

[lenb]

I changed the thermostat some time ago because my RR always ran cool unless towing my tin tent. Since then it has always run at 12:00 but the aircon fans run a lot (not using aircon though). The rad is new and so is the water pump. Is this normal?

Lenb

 

[StuckAgainSteve]

Perhaps a previous owner has done the mod to use the aircon fans as supplementary cooling fans? Don't be fooled by the 12 O'Clock position of the gauge - it's programmed to do that if you in the "normal" operating range - so if you're hovering just under the stage 1 over heat it'll still read "normal".

 

[donp38]

need to check for air con fan mod.
has it still got the viscous fan fitted?
have a look for a small box with a knob on it.

 

[lenb]

I've owned it nearly 5 years and am friends with previous owner who had it for about 3 years. He's not the sort to do an aircon fan conversion but I will ask him. The viscous fan is still fitted and still works. Out of interest where would the 'small box' be?

 

[donp38]

think this maybe an aircon issue and not an engine cooling one.
Datatek will be along at some point, but if you are not aware of the mod, as you know the history of the car.

So the question is, what causes the aircon fans to work so hard?

 

[mcapinha]

Since this is a 2000 DHSE, it already left the factory with the system to switch on the A/C fans for extra cooling. IIRC this is factory spec from MY99 on.

 

[StuckAgainSteve]

Since this is a 2000 DHSE, it already left the factory with the system to switch on the A/C fans for extra cooling. IIRC this is factory spec from MY99 on.

Indeed but I believe they only come on during an actual detected overheat - so the gauge shouldn't be reading normal.

 

[mcapinha]

The fans are tripped off from a thermo switch installed to the 3rd port of the cylinder head. It's a simple on or off switch that comes on at 100ºC.
Is this too high a temperature ? The LR engineers seem not to think so... :lalala:

 

[lenb]

If it is 'hovering' in the first stages of overheat, would the gauge rise when actually towing? Although I haven't been away yet this year I have taken the tin tent for a service (only about a 15 mile journey that included motorway and town) but the gauge still did not go above its now 'normal' 12:00 position.
(Just a bit more info that might help the discussion).

Thanks

 

[Datatek]

The car will indeed have the third sensor at the rear of the head to bring the aircon fans on in an overheat, I believe the switch is set to 110C so should never activate the fans unde normal conditions. It's easy to check if this switch is causing the problem, just disconnect it. It's at the back of the head towards the bulhead.
When you say the aircon is off, is the light lit on the aircon switch? If not, the aircon is on.

 

[lenb]

Hi Datatek,
Yes the light is on. I've just driven home through town (about 6 miles) and the fans didn't come on. However it is typical British summer today - cool and wet - but if it had been warmer they would have definitely come on. I lifted the bonnet when I got in, switched the engine off and was able to spin the viscous fan easily (although there was some resistance). I will check the switch though - when I find it
Don't know if it's significant or not but fuel consumption is not as good as yours! 20 mpg around town - mind you the average speed is only 21 mph so perhaps I'm expecting too much.
Thanks.

 

[Datatek]

Hi Datatek,
Yes the light is on. I've just driven home through town (about 6 miles) and the fans didn't come on. However it is typical British summer today - cool and wet - but if it had been warmer they would have definitely come on. I lifted the bonnet when I got in, switched the engine off and was able to spin the viscous fan easily (although there was some resistance). I will check the switch though - when I find it
Don't know if it's significant or not but fuel consumption is not as good as yours! 20 mpg around town - mind you the average speed is only 21 mph so perhaps I'm expecting too much.
Thanks.

No traffic here The viscous fan test is done with the engine hot and running, if it stops with a rolled up newspaper shoved in the blades it's fecked.

 

[lenb]

It's the fan!!! Just run it up to hot (12:00) and rolled up newspaper stopped the blades easily.

 

[tomcatrr]

It's the fan!!! Just run it up to hot (12:00) and rolled up newspaper stopped the blades easily.

"good news" (you find the why they kick).

Did you keep the fan clutch or "upgrade" to a efan

 

[Datatek]

It's the fan!!! Just run it up to hot (12:00) and rolled up newspaper stopped the blades easily.

The aircon fans mod will get you round that if it's a diesel then you can bin the viscous

 

[lenb]

Update:
Got engine warm enough to start aircon fans and then did newspaper test - blades stopped so easily I could have probably got away with using a feather
Anyway parts ordered from suggested supplier (thanks for info Datatek) and will arrive tomorrow, I've removed the fan and cowl already, so hopefully a fairly straight forward job when they arrive.

 

[mcapinha]

Did you get it warm by driving it around or standing still ?
I'm asking because I'm preety anal about monitoring my head temperature and, even climbing a steep hill with the AC on, it doesn't reach 100C. If the AC fans are kicking in just by reving the engine, there's certainly something wrong with the cooling system and the viscous fan looks like a good candidate (apart from water pump or closed shut thermostat).

 

[lenb]

Did you get it warm by driving it around or standing still ?
I'm asking because I'm preety anal about monitoring my head temperature and, even climbing a steep hill with the AC on, it doesn't reach 100C. If the AC fans are kicking in just by reving the engine, there's certainly something wrong with the cooling system and the viscous fan looks like a good candidate (apart from water pump or closed shut thermostat).

Drove it around in order to get it hot enough! Pump and rad are only a few months old and thermostat was also replaced about 12 months ago. Fan definitely shot!!

 

[lenb]

All Done!
Datatek's mod for the air con fans done, and I must admit I'm a lot happier knowing that the fans are going to kick in at the right temp ..... But what is the correct temp? I've followed the instructions to allow engine to warm up and then switch fans on and back off slightly but how accurate is the temp gauge? It normally runs at 12:00 and did not go above that even with the ecu switching on fans before the mod.
How accurate do you think the new thermostat markings are? It's set at just under 80degs.

 

[wammers]

All Done!
Datatek's mod for the air con fans done, and I must admit I'm a lot happier knowing that the fans are going to kick in at the right temp ..... But what is the correct temp? I've followed the instructions to allow engine to warm up and then switch fans on and back off slightly but how accurate is the temp gauge? It normally runs at 12:00 and did not go above that even with the ecu switching on fans before the mod.
How accurate do you think the new thermostat markings are? It's set at just under 80degs.

Thermostat opens at 80 degrees you need fans setting slightly higher than that.