Toyota Yaris fan keeps coming on

[Marlyn]

Thanks for allowing me to join. Sorry but this is all new to me. We had a motability car for many years so didnt have to worry about things but I lost my husband 2 years ago so motability car went back. I bought a Toyota Yaris which I love! Flown through the last 2 MOT's!!

My problem is I have noticed that the fan keeps kicking in? and its getting worse. There is no temperature gauge to show if the car is getting hot but it doesnt appear to be? Today it seemed to be on constantly? There are no warning lights coming on, car drives lovely, excellent on fuel.

I have googled and its all so confusing. Garage said they would have it in and check it but I cannot afford what may be a huge bill? Is it ok to drive like this? as said, it starts, drives lovely but the fan keeps coming on and obviously I dont want to cause any damage.

Sorry to come across as thick but this is all new to me 😞 My husband would have known what to do!

Thanks for any advice. Marlyn

[Cyker]

Do you mean the big radiator fan in the engine bay?

If you are using the air-con, esp. at this time of year and as it gets warmer, it will kick in whenever you're not moving to help dump the heat from the AC system into atmosphere, and is pretty normal behaviour for all cars with AC.

[Marlyn]

Thankyou for your reply. I'm not sure? I think its the fan that comes on when the car gets hot? I noticed several weeks ago, drove about 3 miles, fine, stopped to collect my Mother, engine still running, then I heard a fan kick in? Stopped after a little while, then noticed it did it again when I was waiting at the traffic lights. Didnt have air con on then as it was cold weather? I have tried reading my manual! but it doesnt really give any information. It has got worse though and today it seemed to kick in and stay on while I was driving. There isnt a temperature gauge? only a little red one that comes on when all the other lights come on on dash when I start the car but they all go out and dont come on again? i.e. airbag light, handbrake, etc.

I did google, and noticed today when I used the air con it wasnt as cold as what it seemed last year? and said the fan may come on if the filter needs changing? I dont go far, only a few miles a day but I'm scared to go too far incase the car is overheating and I might damage something?

[Derek.w]

Marlyn, You still have a radiator overheat light on the dash same light as low temperature just a diffrent colour if it is from memory 104 dergrees or over.

So this will stop you worrying about the radiator cooling fan coming on when you are standing still.

[Marlyn]

When I switch ignition on, all the things light up on dash and there's a little red tem icon, all goes out and don't come back on? so no warning or anything? There's no temp gauge though? 

[Stevie J]

Have you checked the coolant level in the radiator and its expansion tank? The radiator will have a cap at the right hand side on the top, its is right at the front of the engine compartment and usually has a yellow sticker on it saying "Caution" do not open when hot. When the engine is stone cold and hasnt been used overnight, press down on the cap and turn it anti clockwise about a quarter of a turn, then lift it off upwards. You should be able to see the coolant right up to the neck of the filler, in other words the radiator should be full to the brim. Also check the expansion tank, to the immediate right hand side of the radiator - it will have a black plastic cap on it. On the side of that tank there will be 2 markings, Max and Min, and you should be able to see coolant in the tank, in between those 2 marks.

If the expansion bottle is below the Min mark, and the radiator itself is not full to the brim, as you would check by removing its cap (as detailed in the previous paragraph), then you will have a leak on the cooling system, and the car should be taken to a garage immediately, and not used until the coolant has been topped up. You must not top up the radiator with plain tap water - it needs to have proper coolant that you buy from a motor factors such as Halfords, but if the system is low, there will be a reason for this, and you need to have that investigated - it could be a leak from the water pump, a leak from the radiator, a hose, or it could be a failing head gasket. Lack of coolant in the system would cause the fan to come on more often, but may not always operate the overheat red warning light on the dashboard if the fan is able to keep the engine cool enough.

If you are worried about overheating, one way to help it is to turn the heater control to max heat - ie, its red setting on the dial, and turn the blower fan to maximum. turn the output selector to side vents rather than the windscreen or the footwell and open the windows, so the heater in the car will help to reduce the temperature of the coolant.

If you turn the heater to max heat, but the air coming out of the vents does not get hot after the car has been running for over 10 minutes, then that could mean the coolant level is too low in the radiator (which you should have checked as in first paragraph) and is not able to circulate round the engine and the heater  in the car, or the cooling system is airlocked, which is usually caused by leaks, or at worst, a blown head gasket.

One other thing you should do, is remove the oil filler cap on the top of the engine (where you fill the engine up with oil) and look inside the top of the filler cap - if its full of white creamy slime, that is a good sign the head gasket has failed, and that would cause overheating.

[Marlyn]

Wow, thanks, a lot of information there. The coolant in both are fine, no leaks. Checked Oil, that's fine also. The chap that was coming today cant now but he was going to bring a meter thing to check the sensor and also check the thermostat?

Air con all working fine. And car doesnt seem to be getting hot? but this started a few weeks ago, now and then, when the weather was still cold? Thanks for your advice.

[Stevie J]

Thats good, if the levels of coolant are fine then that means you havent got any leaks as you say. The thermostat may be causing an issue if it is not opening properly and allowing coolant to flow round the radiator, as this is what its job is to do once the engine gets warmed up. It is closed when the engine is cold and only allows the coolant to go round the engine block and the heater inside the car, but once the engine warms up, it opens and allows the coolant to go to the radiator.

There will be a sensor located somewhere near the top of the cylinder head which tells the engine computer (ECU) how hot the coolant is. If it gets too hot, the fan on the radiator will be turned on until the sensor tells it to turn off. If the ECU sees the temperature of the coolant is too hot and even if the fan is running, it will turn on the red overheat light on the dash - this is the little red symbol of a thermometer that comes on for a few seconds when you first turn the ignition on before starting the engine. The blue one is the one that comes on before the coolant has warmed up to operating temperature. If the red light stays off, then you should be ok, despite what the fan in the engine bay is doing. 

As has already been said, the fan also comes on often if the aircon is turn on, this is to cool the condenser radiator for the aircon, which is located just in front of the main engine radiator behind the front bumper and grille. The fan is used to cool both radiators and if either one needs cooling the fan comes on.

The state of the filter inside the car that cleans the air before it goes to the vents would not be on any relevance to the fan coming on in the engine bay. If the filter (called the cabin filter or pollen filter) is clogged up and dirty you will just have poor airflow coming out of the vents if the ventilation is turned on.

I hope the guy that is looking at your car can put your mind at rest, and it hopefully ends up being something simple, or inexpensive.

[FROSTYBALLS]

Topic moved to the Yaris forum.