Hi All,

I just had my Rangie in for a regas of the aircon.
The guy doing it noticed the fan at the front did not spin and was advising me to have it checked out by a mechanic.
Told me to leave the Aircon off unless i was going down the motorway as the system would build up too much pressure and overheat. His advice is that if the system builds up too much pressure it will "pop" and cause me alot of heartache/dollareedoos.

From searching on here people have said the fan wont kick in until its a very hot day and your stuck in traffic.
That by driving around 35mph plus the system will stay cool.

So i guess my question is....

Do i just continue as normal and trust the fan will kick in?
Or keep the Aircon off until i am cruising at motorway speeds?

http://www.fullfatrr.com/forum/topic17955.html

MikeG wrote:

What I have understood about this during the last days is that the fan will start when you start the engine but it doesn't stay on all the time... This will depend on the pressure in the aircon system and a pressure sensor will send a signal to the fan when it's suppose to be activated to reduce the pressure...

Your aircon should also work with the fan, downside is the pressure will built up but as long as you are driving the wind will cool and reduce the pressure. When you stop for a while or standing for a traffic light, they recommended me to switch off the aircon as long as my fan has not been replaced.

SteveMFr wrote:

I'll have to take a closer look at the LM's electrics, but generally there are 2 switches on the high pressure lines of an AC (well 3 actually): low/high for the compressor and a somewhat-less-than-high-high switch for the fan (condenser fan all the way in front). Generally, the low / high is somewhere in the vicinity of 2 bar / 30 bar (the compressor will only switch on in between) and 18-25 bar for the electric fan.

Adara, you'll have to wait for a very hot day and traffic (fans only help below ~35mph - if you're going faster, there is enough air to cool the condenser)

From the workshop manual:

Quote:

REFRIGERANT PRESSURE SENSOR
The refrigerant pressure sensor provides the ATC module with a pressure input from the high pressure side of the refrigerant system. The refrigerant pressure sensor is located in the refrigerant line between the condenser and the thermostatic expansion valve. The ATC module supplies a 5 V reference voltage to the refrigerant pressure sensor and receives a return signal voltage, between 0 and 5 V, related to system pressure. The ATC module uses the signal from the refrigerant pressure sensor to protect the system from extremes of pressure and to calculate A/C compressor load on the engine for idle speed control. The ATC module also provides a cooling fan request signal over the K bus to the instrument cluster. The cluster outputs this request to the engine control module (ECM) over the high speed controller area network (CAN) bus. To protect the system from extremes of pressure, the ATC module disengages the A/C compressor clutch if the pressure:

Decreases to 1.9 ± 0.2 bar (27.5 ± 3 lbf/in 2 ): the ATC module engages the A/C compressor clutch again when pressure increases to 2.8 ± 0.2 bar (40.5 ± 3 lbf/in 2 ).

Increases to 33 ± 1 bar (479 ± 14.5 lbf/in 2 ): the ATC module engages the A/C compressor clutch again when pressure decreases to 23.5 ± 1 bar (341 ± 14.5 lbf/in 2 ).

Engine Cooling Fan Control
The engine's electric cooling fan is controlled by the ECM. When the A/C compressor is engaged the ATC module sends a fan speed message between 0 (off) and 15 (maximum speed) to the ECM, via the K bus, instrument cluster and high speed CAN bus. The ATC module requests the cooling fan on when:

The vehicle speed is less than 70 km/h (44 mph).
There is no fault with the A/C compressor clutch circuit.
Battery voltage is less than 16 V.

The fan speed requested depends on the pressure in the refrigerant system. The higher the pressure the faster the fan speed that is requested. When vehicle speed increases to more than 80 km/h (50 mph) the ATC module changes the fan speed request to 0 until vehicle speed decreases to less than 70 km/h (44 mph) again.

If battery voltage increases to more than 16 V for 5 seconds the ATC module changes the fan speed to 0 until the voltage decreases to less than 15.8 V

Thanks Unsolicited!

Is this is the same fan that comes on when the Range is under load?

If so then i know it def works. I did have an extra fan creating a whooshing noise after along day of driving very hilly roads in the heat.
Safe to assume this is it?

Don't quote me, but I think the TD6 has 2 fans. The electric one and an autonomous viscous coupled one that many remove (so I hear?). That is the 'whooshing' one.

The later euro market cars have an electronically controlled viscous coupled engine driven fan only (and no electric ones - those are reserved for 'hot markets'). The A/C can ask the ECU to put the big fan on in those cars instead of the electric one.

So I think you are looking at the electric fans for the A/C on your car? A TD6 owner may be able to confirm.

Outside we have now 33 Celsius in Austria, really hot. Fan is not activating, even in city traffic. IID Tool can not test it, Hawkeye can test the fan, so i tested it. Fan is coming on for test so it is there and living but the car will not activate it. I am pretty sure it should move at these temperatures, any ideas? Thanks!

Anyone has an information?

This summer, same situation. Never heard the electric fan running.
It was really hot outside, 30-35 grad celcius.

What i checked:
Fan is working, testes it via Hawkeye.
Pressure in AC is showing up via Testbook T4.

For my understanding shoukd the fan be kicking in when
you stuck in traffic in the city. Never did on mine.

Thanks!