I'm after a pointer on where to find the temp sender that drives the ECU cooling fan control input - let me explain... in case someone has a better idea!
My 156 2.5 V6 normally runs at between 80 and 90deg whatever the traffic/use, however it has recently started to get to over 100deg in traffic, fans cut in and bring it down again. With the a/con on and stationary it sits nicely at 90deg (fans pulse on and off) and at any speed above about 40 it also sits below 90deg.
Did a bit of diagnosis at the weekend and found a few things out:
1. Both fans should run together, whether slow or fast, and whether driven by the a/con or coolant temp.
2. There are 2 x 50A black relays (in the group in front of the battery) that drive the fans - 1 for fast (the rear left hand relay) and 1 for slow (the one to the right of it). Each relay drives both fans.
3. There are two resistors on the panel behind the radiator, one in each of the fans' slow speed circuit (to regulate the speed) - the upper one of mine has failed, so until I shorted across it, I had no n/s slow speed fan.
4. Whilst my slow speed fans used to cut in at just over 90deg (a/con off), they now cut in at around 105-110deg.
My diagnosis: I only had one fan working at slow speed so need to replace a resistor, but without the a/con on (which I understand uses an a/con gas pressure sensor switch to drive the ECU to turn the fans on) there is no drive signal to the fans until coolant temp reaches 105-110deg (on the dial).
From other threads it seems the V6 has 2 temp sensors, one feeding the temp display dial and the other the ECU uses to drive the fans. So my conclusion is that the one feeding the dial is ok, the one feeding the ECU is on the way out and is under-reading.
Problem is, I can't find them - anyone help??