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[Andy A]

I have two fans. One on the coolant and one on the air con radiator, on my Omega 2.2 petrol 2003. Is this standard?

With the eco switched on. When the engine is up to temperature both coolant and air con radiator fans come on at the same time when at 90 on the dash and then both fans turn off again after temp drops.

If I start the engine from cold with air con on (eco off), both the coolant and air con radiator fans come on straight away and stay on.

I always thought that the coolant and air con radiator fans were independent of each other?

Can some one please explain to me how and when the coolant and air con fans should come on and go off and are they both connected in some way?

I want to understand the system so I can make sure that all is working as it should be before putting her on the road for the first time next week.

Any help with this is appreciated.

Thanks

Andy

[omegod]

The main fan on mine used to run all the time, it was a dodgy fan sensor causing it to run in default mode. Haven't a clue about the air con fan

[05omegav6]

Aircon fan runs when aircon is on, switched by the aircon ecu, also switches on main fan at low speed to ensure air is drawn through the radiator properly, as the aircon condenser generates heat when the compressor is running.

Main fan runs at two speeds, depending on temperature.

If the car starts to over heat then the switches on the radiator override the aircon ecu and puts both fans on full.

At a guess, the lower switch on the radiator is the aircon override and the top one is the main fan

[Kevin Wood]

The bottom switch steps up the speed of the aircon (front) fans when coolant temperature is high, and switches off the aircon compressor if it rises further.

The top switch brings on the rear and front two fans at low speed, regardless of air con status, at high coolant temperature, then switches the rear fan to high speed if coolant temperature rises further.

The top switch is, therefore, the more critical one, since without it the fans won't run.

[05omegav6]

Makes sense, as the top of the radiator will always be hotter...

[Andy A]

The bottom switch steps up the speed of the aircon (front) fans when coolant temperature is high, and switches off the aircon compressor if it rises further.

The top switch brings on the rear and front two fans at low speed, regardless of air con status, at high coolant temperature, then switches the rear fan to high speed if coolant temperature rises further.

The top switch is, therefore, the more critical one, since without it the fans won't run.

Very well explained Kevin. Thank you  Thank you all for your advise and help. 

Know I have another problem. I only have 1 front fan. See first photo.
https://www.flickr.com/photos/53447058@N05/14387144113/in/photostream/

Is the plug in this photo used for the missing fan?
https://www.flickr.com/photos/53447058@N05/14343862306/in/photostream/

Will the engine overheat on long journeys if the missing fan wasn't replaced?

What work is involved to fit another fan back in there?

Thanks

Andy

[RobG]

I only have 1 front fan.

Standard on 4-pot Andy

[Andy A]

I only have 1 front fan.

Standard on 4-pot Andy

Thanks Rob. 

[05omegav6]

If you wanted to fit a second fan you could, but it does involve lifting the rad and condenser out, so probably only worth doing if your car constantly runs hot
That second plug is indeed for the second fan

[Andy A]

If you wanted to fit a second fan you could, but it does involve lifting the rad and condenser out, so probably only worth doing if your car constantly runs hot
That second plug is indeed for the second fan

Thanks for the info.