Thread: Aircon problems Disco 1 Tdi300

Hey mate this might help; it is an exert from another forum, I have heard of it before, and it is something I am wary of having to drive across both the Stuart, and Barrkly Highway's to get to family.

Originally Posted by This is from another forum

Sorry Mike but it is not that simple some cars have one switch and some have two . The part numbers are PRC3359 green dot and PRC3505 yellow dot for a two switch car and just PRC 3505 yellow dot for a one switch car . Which is yours ?
Your does not have to overheat in the traditional way to cause this problem just run a few degrees hotter .
PRC3505 is 94°C / 100°C ie switches fans on at 100°C and off at 94°C
PRC3359 is 109°C / 115 °C ie switches the air con system ( compressor ) off at 115 °C and on at 109°C
The coolant thermostat is fully open at approx 88 °C so if your engine colant is running 12 degrees warmer than normal it will switch the fans on at 100°C and if it cools slightly but is still 6 or 7 degrees warmer than normal ie 94 to 95 °C the fans will never switch off .
This will not show on your cars temp guage as it will never look higher than half way at these values and in fact may actually look slightly below half way and no where near the red .
This slight loss of cooling effiiciency can be caused by , faulty radiator ,ie sludge inside,external fins caked with mud , leaves or corroded away . Same with air con condensor and blocking the flow of air to the radiator . Faulty thermostat both or either in the cars oil system or water system . Water pump starting to fail etc . Could also be a sticking relay in the air con /fans circuit . Possuible problems with leaky cylinder head gasket / cracked cylinder head ( also has other symptons ) etc . My cause was by the oil cooler thermostat opening after the water thermostat and it should have been before Regards Jonathan

This is the forum in question;
Air Con Temp Switch - Land Rover Zone

I know this guy above talks about;
This slight loss of cooling effiiciency can be caused by , faulty radiator ,ie sludge inside,external fins caked with mud , leaves or corroded away . Same with air con condensor and blocking the flow of air to the radiator . Faulty thermostat both or either in the cars oil system or water system . Water pump starting to fail etc . Could also be a sticking relay in the air con /fans circuit . Possuible problems with leaky cylinder head gasket / cracked cylinder head ( also has other symptons ) etc . My cause was by the oil cooler thermostat opening after the water thermostat and it should have been before

But I would honestly suggest a 300TDI pulling a camper trailer at highway speeds would be running warm. Especially when ambient is 43degC and I bet the road temp was at least 65degC... too hot to stand bare foot on anyway!!

Cheers, Adam.

thanks for the reply Adam.
I'll go and check a few of those things. I did blow the expansion tank christmas eve and redid the cooling system. I didn't replenish the coolant but just topped up with water.
I will be redoing the coolant when I fit the low coolant alarm this week.