Overheating warning but not overheated

Hello forum members,

hope that this message finds you all in good health during these days of pandemic.

I have a problem related to my Citroen C3 (make 2004 1.4L petrol). It started some months ago first and it always is random in nature i.e. it arrives whenever it wishes to.
As you can see in the photo, the temperature scale has reached to maximum. However, it did not arrive slowly rather it was a sudden jump from the normal 3 bar position to maximum (red bar). Initially mechanic first re-setted the internal computer memory since there were some errors of cooling fan not working and he also verified that there is as such no mechanical or physical error like leakage or liquid consumption. We also changed the coolant liquid completely just to be sure.

Then even doing about 2300 km of driving in like 10 days (even clocked 140 km/h on German autobahn), it never came but after that a normal drive at around 80 km/h it returned back. Not only this, it also came while driving within the city for less than 15 km. The mechanic again did a diagnosis and got a hint from someone that it could be the engine cooling fan resistor that was faulty. We also changed that.

Now after changing that, doing some road trips even on mountainous roads, it never came but again doing a normal city drive, the error returned.

I personally did a diagnosis that when this error comes, the air conditioning does not work at all. Like the internal fan switches on but the air conditioning does not function.

What do you guys think? A quick answer would be really really appreciated since I am planning to go back to the mechanic soon.

haroon88 wrote: ↑Mon Sep 07, 2020 4:39 pm What do you guys think? A quick answer would be really really appreciated since I am planning to go back to the mechanic soon.

Hi

Temperature sender faulty.

Change the sensor.

C3CAR wrote: ↑Mon Sep 07, 2020 5:05 pm Hi

Temperature sender faulty.

Change the sensor.

Thank you very much. I will try this.

C3CAR wrote: ↑Mon Sep 07, 2020 5:05 pm Hi

Temperature sender faulty.

Change the sensor.

However, how can a faulty sensor could make a fan not to work? It is just bugging me for which I am writing this reply. Shouldn't it be a faulty fan circuit or something related that is not letting the fan to work and hence the air-conditioning as well?

haroon88 wrote: ↑Mon Sep 07, 2020 8:17 pm

C3CAR wrote: ↑Mon Sep 07, 2020 5:05 pm Hi

Temperature sender faulty.

Change the sensor.

However, how can a faulty sensor could make a fan not to work? It is just bugging me for which I am writing this reply. Shouldn't it be a faulty fan circuit or something related that is not letting the fan to work and hence the air-conditioning as well?

You wanted a quick reply and the temperature sensor fault is going to give a false display and that's a quick answer, quick to change and probably doesn't need a mechanic.

You are taking the car to a mechanic later and they can do diagnosis on the fan circuit and the associated computer control if the sensor change didn't give the expected results.

There are lots of topics here about faulty engine fans, no a/c, and none of them are quick, but you are welcome to read them all.

As a technician I can tell you, trying to find one item to explain ALL of your faults will bend your brain! Sometimes its just one fault and some times its multiple.
Start with the most serious fault and solve that first. In this case it appears to be the temperature sensor. It could be the connector or the wiring. Inspect the area around the sender first, look for things that might be wrong. If it all looks ok replace the sender.
When all the bars light up on your dash your thermo fan should run. If it doesn't you probably have a problem with the fan speed controller. It cant be repaired, you need to replace the whole fan assembly. It could be the wiring or the engine ECU but the speed controller is the usual suspect.
Yes, it could be the fan speed controller causing your A/C to not work but there may also be something wrong with the A/C system! Solve one problem at a time.

Ozvtr wrote: ↑Mon Sep 07, 2020 10:17 pm As a technician I can tell you, trying to find one item to explain ALL of your faults will bend your brain! Sometimes its just one fault and some times its multiple.
Start with the most serious fault and solve that first. In this case it appears to be the temperature sensor. It could be the connector or the wiring. Inspect the area around the sender first, look for things that might be wrong. If it all looks ok replace the sender.
When all the bars light up on your dash your thermo fan should run. If it doesn't you probably have a problem with the fan speed controller. It cant be repaired, you need to replace the whole fan assembly. It could be the wiring or the engine ECU but the speed controller is the usual suspect.
Yes, it could be the fan speed controller causing your A/C to not work but there may also be something wrong with the A/C system! Solve one problem at a time.

It’s nice to talk and listen to an expert so I am thank you immensely for your expert opinion. Very well put!!!

Let’s hope it is not that of a problem difficult to resolve.

haroon88 wrote: ↑Tue Sep 08, 2020 8:10 pmIt’s nice to talk and listen to an expert so I am thank you immensely for your expert opinion. Very well put!!!

If you look at the top right of posts there's a thumbs-up icon, this is your opportunity to thank the author for a helpful post. It's always nice for contributors to get a 'thank-you' especially as all help is given willingly and free of charge as is use of the forum.