Only had this car for 6 weeks and it's been pretty cold here so I didn't notice this problem until a few days ago when it warmed up. Sitting in traffic the temp started rising although it never actually hit the red, nor did I overheat with steam etc. I connected my OBDII reader and the temp reached about 225 but no higher, though I'm afraid when spring actually arrives it might overheat.
I have checked and I have enough coolant, no apparent leaks. What I did notice is that the electric radiator fan is not coming on as it should. It won't come on when AC is on either at any temperature. I have checked the obvious things like the fuse and the relay (swapped it with known working AC blower relay) and it still doesn't work.
I was thinking that my ECT sensor is probably ok because the fan doesn't work with the AC on and I get a reading via OBDII. With the AC on, I removed the fan relay and tried removing/reinserting it a few times to see if I could hear/feel it click (verifying that it is trying to work the fan) but I get nothing. Makes me think the ECU is not commanding the fan to work like it should?
With the car running, unplug the connector on the coolant temperature sensor, near the upper radiator hose outlet. The fan should come on in 3 to 5 seconds if all else is working. This will likely also trigger the CEL, but that will go out when you reconnect the connector.
I had to replace the fan motor on my '01 Z24.
In coolish weather it ran fine, but when I turned on the AC (to fix it) as soon as I noticed any heat in the condenser, the engine overheated and blew the coolant cap out of the reservoir.
That's how I found out I had a bad fan motor.
Ebay has 'em for cheap if you want Chinese.
I paid about $45 for a made in Canada motor.
From the factory fan is programed to come on at 223/224 degrees. So is it coming on at the 225 degrees?