Rad fans not working once temp hits 97

[TehAgent]

As stated in the topic title,

Me radiator fans don't kick in once the engine comes up to temp, and with warmer (hopefully) weather on the way, I'm going to need them buggers to come on by them selves.

I heard there is a temp sensor near the gear box somewhere, but with out dismantling the air filter box, i cant see the little thing. or am i in the wrong place completely, also is there anything i can do to test the sensor? before i make the trip down to my Local store to get a new one.

Both fans do work, as i have jerryrigged a on/off switch just inside the bonnet. but I've already left the damn thing on twice, and had to recharge the battery all relays on the fans them selves have been replaced, and the connectors cleaned up.

any help would be most appreciated. (car model is in my Sig)

[gRoberts]

I had this problem in my Vauxhall Astra. Basically the thermostat stayed open or closed, thus some how stopping the fans from working, which in turn killed the car (mayo in the rocker cover.)

What was suggested was to remove the thermostat from its housing and put it in warm/boiling water. If it opens or closes when in hot water its working, which means there could be a problem else where.

Your friendly haynes or another member would be more help.

[mjb]

My tubby only had one working fan. It used to come on full power at about 100 and turn off just left of the centre mark (can't remember what that is)

[teamster1975]

My tubby only had one working fan. It used to come on full power at about 100 and turn off just left of the centre mark (can't remember what that is)

Doesn't the other one fire up when you're using the aircon?

[steve_earwig]

Shouldn't there be an ecu? And what about this Bitron sensor? If there's two fans then it has air con and it should run them in series or parrallel when the air con's running, regardless of engine temp.

[TehAgent]

biton unit, which one? as far as I'm aware, there are two (modal depending) one is located in the most stupidest of places (inside the passenger side wing UK car) and the other behind the glove box.

The one behind the glove box has been changed recently due to no working speedo, that now works.

The fans have never worked since i got the car last year in September, luckily its been cold enough not to put them on very often, the only time I've had to put them on is when caught short in the usual Weekday mid morning road works (why they don't do road works at night is beyond me, they do in Germany).

Yes it has A/C An no i don't think they come on when its switched on, though saying that, I've had no reason to put the A/C on over winter so will need to check.

Where abouts is this temperature sensor, the Haynes manual, in all its infinite wisdom, only shows a very hard to see black and white photo of a location somewhere in bognor regis with a few wires sticking out and i didn't find the description helpful either.

[steve_earwig]

I suspect that calling the ecu that runs the speedo Bitron may be an error, I binned my old one though so I can't say what's written on them.

Haynes, "Cooling, heating and ventilation systems", section 6 "Electric cooling fan thermostatic switch - petrol models with air conditioning and all diesel models." "10 The cooling fans are controlled by the "Bitron" sensor." Hmm, says it's on the thermostat housing. Is the b&w picture which you refer to figure 6.11?

The wiring diagram just shows it as having two switches inside, presumably thermoswitches for low and high speed, but it doesn't show any relationship to the air conditioning, nor is there a diagram for the air con either (thanks Haynes ). It's earth switched though, are you getting any positives on the relays? If you can find this mythical Bitron sensor, you could test the leads running away from it, if Haynes is in any way to be trusted you should have one earth and two showing relay coils via positive (some voltage but not 12v) but bear in mind there could be a lump of electronics somewhere downstream.

[teamster1975]

Come to think of it I don't think both have ever come on in my car, I shall have to investigate just in case we get a summer this year!
I know a fan always comes on when I turn the aircon on.

[mjb]

My tubby only had one working fan. It used to come on full power at about 100 and turn off just left of the centre mark (can't remember what that is)

Doesn't the other one fire up when you're using the aircon?

Didn't...

Nah it looked like the fan motor was dead on it so I just had one fan going at 100% or nothing

[steve_earwig]

They're suppose to run in tandem - full speed, half speed and no speed the same.

[teamster1975]

They're suppose to run in tandem - full speed, half speed and no speed the same.

Bollocks, one of mine is shot then.

[mjb]

They're suppose to run in tandem - full speed, half speed and no speed the same.

Bollocks, one of mine is shot then.

Yeah the relays are basically laid out so they can run in serial for half speed, or parallel for excessive noise levels. Worth checking both fuses (the fusebox with the BIG fuses, next to the battery that i have trouble getting my fingers to to unclip) and the relays (swap them around) as getting at the fans themselves is apparently a radiator-out jobbie

Mine did billions of miles on just one fan though so you may decide to just not bother ;)

[teamster1975]

Thanks Matt, I'll investigate!

[steve_earwig]

Please won't somebody tell me if this is any help?

[rapport25]

Not all pugs have two fans, mine is a hdi with only one fan