picasso c3 over-heating?

[piki]

Hi
i have the picasso c3 2012 , lately i have this problem when it whould over heat if i stand in red light or standing anywher , if i drive it, it wont over heat.
it shows the warning light within 20-30 sec since i start the car .
last time it did this it was like 6 month ago , i changed the thermostat and problem solved , i have tryed also today to raplace the thermostat , but no luck.
i have change the temp sensor with the thermostat, what else could it be?
fyi i did timing and water pump few month ago , since then , i had no problem .

[piki]

any1?

[GiveMeABreak]

When you did the water pump, did you drain the cooling circuit, as this should be done - so the next logical question is have you filled it with the correct coolant and then bled / degassed the coolant circuit? If you haven't, then you may have the wrong type of coolant in and / or an air lock in the circuit that can lead to overheating.

[piki]

i did drain the cooling ,
i did more digging today.
it wont over heat if i drive it , or even stand without the ac on .
but , if i put the ac on on idle , 5 sec exactly after the fan go in , it goes out , then the warning light with stop light come on.
the temperture by the ecu (obd2 connected is 80c).
i drove it today , put the ac on , it showd the temp light warning and stop , and after 10 secends its disappear.
again -if the ac is off , it will not overheat , if i turn it on like 15 secends it will throw the warning

[piki]

Btw - i replace the radiator today , no luck as well

[piki]

ok so i left the car for like 5 hours , came back now , start it up , turn ac on , 30 sec after , warning showed up , (engine cold-like 18deg cel outside
is there is any temp sensor on the radiator or somewhere else , beside the one that on the theremostat?

[GiveMeABreak]

What is your vehicle's VIN? I need this to identify your exact engine and system. Please post it here (it will be masked automatically when you submit your post).

[piki]

VF7**************[VIN obfuscated, can be read by forum staff]

[piki]

Maby the coil on top of the radiator is controlling the temp sensor too??

[GiveMeABreak]

See my post here for a C3 for the water temperature sensor location item (2): it is the same part number and marking as the one in that post.

viewtopic.php?p=632862#p632862

[piki]

Yea i have replaced it , and im pretty sure i have found it , the coil on top of the radiator is defective , and it couse the temp light, will update soon