2004 Ford Fiesta Radiator Fan Not Kicking On

[stanos01]

Hi all,
my 2004 1.6l petrol ford fiesta recently overheated while I was stopped in bad traffic on a hot day. After waiting for it to cool down, when driving home I noticed that the temp guage would increase whenever I was stopped, and drop back down when I started moving again. When I got home I noticed that the radiator fan wasn't on like it usually was when I stopped the car. The fan would turn on however when I turned the aircon on. While trying to diagnose the issue, I accidentally broke the coolant temp sensor which was very old and fragile, and had to replace it, but while the coolant temp sensor was disconnected, the failsafe kicked in and the fan turned on and stayed on. I checked all the fuses related to the radiator fan and they all seemed fine. After replacing the coolant temp sensor and bleeding the system, the same problem seemed to still be there, but I recently noticed that the fan no longer turns on with the aircon, and also doesn't turn on when I disconnect the coolant temp sensors. Does anyone have any ideas on how to solve this? Otherwise I have given up trying myself and will take it to the mechanic.

 

[Handy Andy]

Breaking the coolant temp sensor - even replacing it and if the wire was broken (open circuit) that fan would run no matter what.

Do you get a temperature indication on the system when you operate the car?

IF the sender was the wrong type or bad, it may show full scale or maybe a segment when it was blazing hot - then you know the sender is not the right one - you'll need the one for your VIN don't just presume the person at the counter is going to know what motor and it's displacement is - unless you supply a VIN. Because as it stands right now, you may have to deal with a 19-year old kid that has no clue to what your car is - even though they were both born in the same year.

If So - take off that connector to the temp sensor, and check to see - via ohmic check - that connector wire is somehow shorted further back in the loom. Check using your DVM on 200Ω setting - see if it reads any measure ohmic results - should show Infinite (1.000 or OL Open line).

If you get an ohmic reading - then the wiring may have shorted (or) the wire is shorting out the voltage being sent to it when the engine is running - then that problem is in the harness itself.

OR...

You can also check the sender itself - test from one lead across to engine ground and see if a reading shows - if it shows nearly a dead short, the sender is more than likely bad or the wrong type of this engine (the ECM is built for a "range" of voltage return from it's sense line to that sender - if it's out of range - that sender is the wrong type or has the wrong ohmic range of variable that the PCM is not set up for,

 

[stanos01]

Thanks for your help, I ended up taking it to a mechanic who diagnosed it as a faulty radiator fan, that would only work intermittently. I replaced the radiator fan with a new one and it has been working fine since so it appears that that was the issue.

 

[Handy Andy]

I replaced the radiator fan with a new one and it has been working fine since so it appears that that was the issue.

Even better!

Seems the mechanic you went to was able to see the housing and know the fan needed service...

• ...Since none of us - could not see the condition the fan and it's housing was in, it's a tough call - we presume many things are checked out and written off as - good - passed now onto the next thing - before we even see a post about anything - some posters do check and rule out specific things; we simply cannot presume even the simple stuff as being the cause unless the poster has checked and ruled them out...

Was hoping it wouldn't be an expensive fix but knowing the fan was bad - causing this - glad to see you're back on the road!