overheating!

[Matt 16v]

the radiator fan doesnt engage when my car gets hot, i have replaced the resistor pack so far

i know the fan works, i've tested it.

the radiator is hot and the coolant is circulating round the system, the fan just doesnt wanna come on.

is there anything else to check?

 

[The Fatty]

dosnt the fan have a fuse somewhere? might be dat...

 

[MrMark]

has the warning light actually came on in the dash?

 

[Matt 16v]

yeah, stop light with a pump symbol on it

 

[MrMark]

must be a sensor or a fuse, then.

testing by process of elimination, is ur best bet. unless u know what ur looking for.

 

[Matt 16v]

what are the sensors i should be looking for? i'll start off checking the fuses i think

 

[Matt 16v]

all the fuses seem to be fine

 

[mini-valver]

Thermostat most probably, id check fuses first though!

 

[Matt 16v]

fuses are ok, the rad is getting hot so im not sure its the stat, what else could it be??

 

[Matt 16v]

anyone know what the other sensors in the cooling system are??

 

[donsrno1]

I don't know about the cooling system on the Mk2's, but on Mk1 clios there is a sensor that goes in the side of the radiator and this controls when the fan comes on and off. I would imagine there will be something like this on yours and if you have tested that the fan works, and you know the radiator is heating up I can't see what else is could be tbh.

 

[Matt 16v]

think thats the part i've just replaced, it fits in the fan shroud on the radiator and has a coil and resistor inside

 

[Matt 16v]

bump :dapprove:

 

[MrMark]

best get it to renault mate. Seems we cant be much help on this occasion.

 

[DrR]

Random Q, but how hard is it to make this fan come on? Cos every car i've ever owned never known the fan to come on??

 

[Matt 16v]

the fan used to come on all the time on my valver, i'd never really noticed until recently thinking about it, but in the few months i've owned the 172 the fan has never come on

will they charge me to diagnose the problem, or is it just gonna be plugging in a fault code reader?

 

[BrianR]

As far as I am aware, there is only a fuse (which is in the e-box under the bonnet) a relay behind the passenger side fuse box, and a temp switch (which is in the rad) controlling the fan.

If you pull the plug off the temp switch and short the pins out the fan should run.

If it doesn't, suspect the fuse first then the relay.

Check the fan will turn as sometimes they can jam in the shroud.

 

[Matt 16v]

thanks Brian i will try it, the recovery guy tried shorting the connection to the fan but it still wouldnt turn so he ran a lead from the positive battery terminal to one of the pins and it started to run, I replaced the resistor pack based on his advice but it hasnt worked, could one of the relays have prevented the fan from engaging (ie if its stuck closed)

do you know which relays to try?

also how do you test a relay or is it better to just replace??

 

[BrianR]

As far as I remember Matt, there are three connections in the plug to the rad-stat. The fan, according to the manual, has two speeds, so you would have to short out the right two to get it working.

I will have a look at my Sons car when he gets home tomorrow if thats soon enough for you.

 

[Paddy_g46]

sounds like a dodgy themro switch

 

[Matt 16v]

Cheers Brian

are the relays expensive?, if i can find out which one it is i'll try replacing it and see if that works

Patrick, wheres the thermo switch, thats not what renault call the resistor pack is it?

 

[BrianR]

I think its just a standard 5 pole relay in which case a few quid. I will check on my Sons car tomorrow.

The "thermo switch" is the temp switch on the radiator we were talking about shorting the plug for.

 

[Matt 16v]

thanks Brian, i'll try replacing that then, if it is a standard one, a few quid is worth it just to rule it out (if u can tell which one it is)

so the thermo switch is the resistor pack then, already replaced that thing

i'm just hoping its the relay, if it was the stat then the radiator wouldnt get hot would it?

 

[BrianR]

Whoa up Matt.......the thermo switch is nothing to do with the resister pack, thats a heater fan speed control device.

Its the temp sensor is on the water coolant radiator that switches the fan in front of the radiator, ON, when the engine temperature rises above a preset limit. Nothing to do with the cars heater.

 

[Matt 16v]

ah, that makes more sense, what does the thermo switch look like? and is that its real name? does it screw into one of the coolant pipes?

i should probably replace that, i thought the thing with the coil and resisitor was the temp switch lol

 

[BrianR]

Its not commonly called a thermo switch, its really a Temperature or cooling fan switch.

I had a quick look at a parts list and i noticed there is also mention of a resistor unit to control the 2 speeds of the fan. It would appear to be on the bulkhead behind the engine.

I would much prefer to check all this against my Sons car when he gets home later, rather than guess. If thats OK with you.

 

[Matt 16v]

thats fine with me

thanks for your help

 

[BrianR]

Matt, this is what I was referring to........

 

[chris c]

have you changed the coolant recently?

if so you may have created an airlock which will need to be got out. leave it running with the cap off the header tank and the water will eventually boil and release the air.

an air lock will stop the coolant flowing properly and it won't get to the temp sensor

 

[Matt 16v]

ah, i havent changed the temp switch, might have to invest in one of them

Chris i have changed the coolant, but that was after it over heated the first time, and when i changed it, i did what you said about leaving the cap off to get rid of any air

but i can certainly try it again, as it wont cost me anything to test it

 

[Matt 16v]

Matt, this is what I was referring to........

had a quick look and that socket for the temp switch is blanked off on my car

 

[Josh@Renparts]

low temp sensor? the one bolted into the side of the rad...?

 

[Matt 16v]

I cant see any sensors bolted into the side of the rad, all the air con pipework is running around it, and the area that Brian has indicated in his diagram is blanked off, I guess the coolant temp sensor is located somewhere else on models with air con?

 

[BrianR]

I looked at my Sons car and there is definitely a temp sensor switch with 3 wires as shown on the diagram I posted. It is under the air filter box and very hard to see.
The resistor pack is on the bulkhead and equally inaccessible.

His car has air con so there shouldn't be any difference.

I am stuck now, not sure how i can help further. ....... Sorry.

 

[Matt 16v]

thanks Brian, you've been a great help, I'll go have a closer look, if i cant find one, i'll get renault to tell me where it is.....well i'll try. lol

 

[Matt 16v]

I've taken some pics of the sensors nearest to the rad, maybe someone can tell me what they are, i've just replaced the sensor in pic No.3 last week and it didnt solve my problem.

what are the other two sensors? is No.2 something to do with the air con?

 

[BrianR]

Thats the one, in picture 3 !! Pull it off and short the green wire to the blue wire then the mauve wire. The fan should run (ign on)
If not, as the switch has been changed, you need to look at the resistor.

 

[Matt 16v]

just tried that, i could only get it to come on by running a wire from the positive terminal on the battery to the second connector, it wouldnt come on when touching the 1st connector on the socket.

 

[BrianR]

Then your looking at a supply problem if there is no power in the plug.

FUSE is my first reaction. I have attached the circuit diagram for you, as you can see the fuses are in the engine compartment E box.

 

[MrMark]

Brian has made it his misson to solve this problem!