Fan won't cut in ?

[gadgetman]

Driving around today temp gauge went into red when sitting in traffic,pulled down the road a bit and switched off the engine.After a a couple of minutes started back up and the gauge was out of the red and drove down the road and it went back to normal. when I got back home left the engine running and it went back into the red again.

I have checked the fan and when it is shorted out (where it connects to fan switch) it comes on and runs fine.

I have an new thermostat (cool running)
new radiator fan switch
new antifreeze

Anyone got any ideas? A part from this everything else is running fine.

At which point should the fan be cutting in halfway or 3/4?

[easytrans]

Re: Fan won't cut in ?

Silly question ... but did you fit the thermostat ? and if so are you sure you fitted it correctly (not installed backwards?).

Can you remove and test the fan switch, attach a tester or test bulb across the switch while submerging in a mug of boiling water .......

Maybe there is a blockage? did the radiator feel HOT when the gauge was high ?

Laurie.

[Pigeonrat]

Re: Fan won't cut in ?

If the engine's being cooled correctly when driving, it only overheats in traffic, and bridging the terminals at the fan switch brings the fan on, I'd have said it can only really be a faulty fan switch, new or not. A stuck thermostat or blockage theoretically would cause it to overheat (or at least run hot) while driving, and the fan motor and wiring appear to work fine. As Laurie said, test the switch in boiling water and see what happens...

[gadgetman]

Re: Fan won't cut in ?

Right just been outside and had a look. Started engine & let it warm up. Bottom hose got hot, top hose hot, rad hot(top and bottom). It took about 10-15 minutes to warm up. The fan still did not come on. I disconnected the radiator fan thermostat sensor/switch and shorted the wires to the fan and it spun up ok. Left it for about a minute and the temperature went straight back down. So I think it is the switch.

1. My next question is if I am running a cool thermostat 82 degree do I need a different switch ie the 87-82 degree one or should it be ok with the 100-95 degree.

2. Would I be better off just changing the thermostat back to a normal 92 degree?

or could it be something else?

engine is c20xe

[Astra Dan]

Re: Fan won't cut in ?

Renew the switch, and fit a standard 'stat. It's a bodge to get more fuel in.

[Pigeonrat]

Re: Fan won't cut in ?

Agree with Dan. There's no point having a cool stat on a road car anyway IMO - but get a genuine Vauxhall thermostat (or Wahler, who make them for Vauxhall in any case), not expensive and far better than the crappy pattern stats which tend to die in under a year.

[DarrenH]

Re: Fan won't cut in ?

the non cool running stat you mean.

the worst bit about them is that i still havent managed (in 10 years) to find a short and elloquent way of describing to people that they dont actually make your engine run cool. they certainly make it run cool when the engines not generating much heat (i.e cruising high speed) but thats counterproductive.

my observations, engine temp never gets out the blue sector normal driving, uses more fuel, runs too cold, more engine wear. temp rises up to normal running temp when pushing engine hard, swings wildly between cold and hot sitting in traffic.

the fan switch itself is ok being standard temp range, as the fan is supposed to be an auxillary device anyway. dropping the cut in temp will make it run pretty much all the time which isnt ideal.

[Jags C20LET]

Re: Fan won't cut in ?

Hi all. I fitted a lower cut in temp switch because after fitting a frontera ic, ( the ic also requires the install of the mk3 diesel rad, which is smaller than the standard let rad), i found that the engine was getting hotter faster and the fan was on and off alot more than before...prolly due to the ic reducing airflow to the rad. The lower switching temp was an attempt to reduce the running temp by making the fan come on earlier.

Was this a good move or not?

[easytrans]

Re: Fan won't cut in ?

Well its basically the thermostat that controls the temperature of the engine, opening up to take in cooled water from the radiator so if your assisting your radiator airflow then that can only be good. Again the thermostat will (should) only pop open when the temperature reaches optimum and then will close once a slurp of cooler water has brought down the temperature below the optimum.

If that makes sense ?

Now what was the question ????

Laurie.

[gadgetman]

Re: Fan won't cut in ?

I now have a standard GM thermostat and radiator fan temperature switch, but the fan still won't kick in ?


Bottom rad hose goes hot then rad goes hot then top hose.Thermostat kicks in and I see the temp fall. If I leave it running about 5-10 minutes more the temperature goes back up into the red again-but no fan. If I bye pass the fan switch(short the connection with some wire) the fan turns on and the temperature goes back down.

Anyone got any ideas?

[tiff_lee]

Re: Fan won't cut in ?

Is the temperature uniform over the radiator?

You have proved the fan control circuit works by shorting the plug to the fan switch so the fan isn't cutting in because the switch is NOT making. Now whether the switch isn't making because it is duff (new or not) or whether it is something to do with your rad is what needs to be diagnosed.

[easytrans]

Re: Fan won't cut in ?

Can you test the switch as it heats up with either a meter or a bulb and wire just to confirm that the switch is (or is not switching) as the temperature comes up

Or one of then hand-held thermometers pointed at the switch may give some clues.

I doubt an air lock in the Rad, was there any plastic cover on the switch when you fitted it that could prevent it working? Is the switch the correct item for your car (90340497 for the 20XE and is a switch with a pigtail wire attached)?


Laurie.

[Pigeonrat]

Re: Fan won't cut in ?

Barring another dodgy switch...well, radiator partially blocked maybe? Or it could be a broken wire at the fan switch, which makes contact while you're fiddling with it, but at the angle it sits at when plugged into the switch is enough to break contact. It's getting weird though, this one.

What I would do now - have you got a multimeter or test light? If so, disconnect the fan and connect the meter (on continuity setting) or lamp across the switch contacts. Run the engine up and see if the switch works. I would expect on a healthy GTE for the fan to kick in while the temp gauge shows 1x blue and 2x yellow blocks, maybe 3x yellow blocks on some cars. If you go beyond this point and the meter/lamp shows the switch has activated, then given that the fan itself works, it can only really be a break in the loom. If the switch doesn't activate even when the engine gets close to overheating, take it out, make a pair of leads with a spade plug at one end, plug them into the switch (and your meter/lamp at the other end) and boil it up in the kettle (don't burn yourself). If the switch activates as the kettle boils, it suggests a blockage or other problem in your radiator. If the switch still doesn't activate in boiling water, it's yet ANOTHER dodgy switch, but really, that would be surprising. Good luck.

[gadgetman]

Re: Fan won't cut in ?

switch-90340497
thermostat- 90443472

[DarrenH]

Re: Fan won't cut in ?

all else being equal and correct, maybe the engine isnt actuall getting hot enough to kick the switch, but the thermistor for the digidash is lying and/or engine earth issue