HELP - has my radiator fan killed the battery?

[RichardH]

Morning all,

I've got a problem on my V6, which I gather (from a response to a query over on the .COM Forum) could be either a fault with the temp sensors/switches, coolant pump, battery or alternator. I'd like to get a clearer picture before taking it to the Vauxhall garage, in case they tell me it's ALL of the above, and charge me accordingly ....

Anyway, what happened was: the radiator fan has started cutting very quickly - even when the engine temp isn't above 'normal'. Not only that, but it keeps going long after the engine is turned off*. I came back to the car on Friday to find a flat battery... and even after driving for a while on Sat, the battery was flat again yesterday.

(*The only thing I could do to stop the fan going was to the restart the engine for a couple of minutes after parking.)

I don't know whether the fan's behaviour is a CAUSE or an EFFECT of any battery/alternator problem. The warning lamp hasn't come on to indicate a faulty alternator (although the one for a failed brake lamp has come on for some journeys - even though no bulb has failed ...).

Any advice appreciated.

R

[vauxhallman]

Sounds more like the fan thermostat has gone to me, I can't see why anything else failing should cause the fan to come on, but if the fan is coming on like that it will flatten your battery sooner or later.

[Robert_Dale]

Sounds more like a crossover on the electrics (power getting to the fan when it shouldn't be - possible a failing relay?)

I would suggest getting an auto electrician out before you got to vauxhall first (bout 30 squid for an electrician).

I wouldn't say that fault is a battery or an alternator fault

[Stupink]

The fan stat is connected to the radiator, so if the fan comes on and cools the rad, it should cool the sensor and switch it off, whether the coolant is being circulated or not, the temp sensor is in no way connected to the function of the fan! only the dash display.
So in short, the fan coming on /stayin on, is more than likely the thermostatic switch in the rad, if you know from the fact the car hasnt been running long that the in dash display is right and the car isnt hot yet and its coming on, then yeh. sounds like it needs replacing.

The fan staying on could obviously flatten your battery, It *could* also potentially kill it if it isnt in good health already, batteries do not like to be completely drained.. However it is far more likely that it is just fully drained, and thus its not charging well, you NEED to remove it and plug it into a mains operated battery charger for at least 48 IMO after a battery has gone completely flat, it probably wont start to charge even for the first few hours as it cannot pass a current barely when completely flat.

So.. IMO.. Take the batt out, recharge it over 48hours, fit a new stat switch and see how it goes.

[RichardH]

Thanks for the tip Stupink. I'll have a look through the Haynes manual* tonight and see what it says about the thermostatic switch.

(*Hopefully, it's not a V6-specific operation, otherwise Haynes won't help)