Strange Aircon Fan Behaviour

[Mrrnoname]

Hi All,

 

Car in question is a Mk1 Skoda Fabia 1.9 SDI Classic with air conditioning. For the first time in around a year I turned the air-con on today. It's functioning and the air is cool (although I don't think as cool as previous years).

 

The engine bay has two fans, a larger one on the right and a smaller one on the left (when viewed from the front). When the air-con is on, the smaller fan is continuously on, the larger fan alternates between being off for around 20 seconds, then on for 10 seconds. I don't remember the fans behaving like this in past years but it's possible that I haven't noticed. This happens regardless of engine temp. Outside temp is 25 degrees C. As soon as the air-con is switched off both fans remain off.

 

Is the larger fan supposed to alternate between being on and off like this continuously? It seems like strange behaviour.

 

 

Thanks in advanced!

 

 

[Breezy_Pete]

What year is the car?

 

Does the large fan seem to go pretty fast when it does come on, like loud and furious? It sounds to me like the large fan has had it's low-speed resistor fail. This seems very common. When this happens, it goes straight from off to high/full speed operation, when the refrigerant pressure goes above a certain threshold (16 bar).

 

Check how many wires come from the back of the smaller fan, to the three-way connector near the bottom corner of the fan shroud, some of these are two-speed (three wires from fan), others single speed (two wires from fan motor).  If the small fan is only single speed, there's no resistor internal to that one, so the fix is easier.

 

See: http://www.briskoda.net/forums/topic/404143-radiator-fan-repair-courtesy-of-vortex-here-and-uk-mkiv-forum/

Edited 17 July, 2016 by Wino

[Mrrnoname]

Thanks for your response.

It's 2003 Reg. Yes the larger fan does seem to come on at full speed. It's much louder and faster than the other one. I'll check the number of pins on the smaller fan but that one seems to be working ok. Thanks for your help.

Edited 17 July, 2016 by Mrrnoname

[Mrrnoname]

Hi all,

To complete this thread - it was the main (larger) fan's inbuilt resistor that had failed. A replacement fan resolved the issue. Both fans now run at slow speed continuously when the air-con is on (fans start a few moments after it's switched on, not instantly)

Replacing the fan was fairly easy (three screws and a connector at the bottom right) however required the car to be jacked up to reach the lower screw that secures the fan in place.

[Dazza95]

Thanks for letting us know the outcome. I'm going to be buying another Fabia soon and the condenser fan is definitely something I'm going to check, it seems to be a common issue.

[Breezy_Pete]

Hi all,

To complete this thread - it was the main (larger) fan's inbuilt resistor that had failed. A replacement fan resolved the issue. Both fans now run at slow speed continuously when the air-con is on (fans start a few moments after it's switched on, not instantly)

Replacing the fan was fairly easy (three screws and a connector at the bottom right) however required the car to be jacked up to reach the lower screw that secures the fan in place.

 

Well done on fixing it so fast.  How much was the replacement fan, if you don't mind me asking?  Although the (externally added) resistor fix is dead cheap, it is a bit of a faff, especially if you're not confident with wiring.  Hopefully fan manufacturers have improved their resistor implementations in the last ten years or so.

[Mrrnoname]

On 22/07/2016 at 18:08, Breezy_Pete said:

Hopefully fan manufacturers have improved their resistor implementations in the last ten years or so.

 I guess not, six years later and the resistor has failed again. Currently trying to locate another fan and came across my own post 😁

[Breezy_Pete]

Not tempted to mend it with external resistor?