Recently bought a 2005 Uplander. Assuming that the engine temperature gauge reads as Cold-0, Hot-1 and Middle-0.5, when the car is in operating temperature, the needle for engine temperature sits a fraction of right hand side of the middle, say 0.52 based on my assumption. It sometimes overheats while idling. The needle starts to move to hot area slowly and as soon as I turn on the AC, it goes back to normal operating place (0.52). Recently, the coolant has been changed (radiator not flushed), and thermostat has been replaced since the needle was sometimes bouncing back between 0.42 and 0.52. What can be the problem? Do you think still it can be a problem with the thermostat?
I appreciate for any input.
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You say they both work once you open the A/C. This is normal except that one of them comes on if the engine temp goes above a certain point regardless if the A/C is on or not. Check that sensor for proper operation.
The thermostat was changed by a mechanic. I bought an aftermarket one and I watched him during the work. But the needle being a little bit on the right hand side of the middle almost 99% of the time is not normal isn't it. Do you think is it because of the thermostat?
oldchevy, Do you know where the sensor located for the fan?
It probably doesn't hurt, new thermostat and coolant. However, the gauge in the I/P cluster is not meant to be a precision instrument. It it were me, I'd first hang a scan tool and "calibrate" the gauge by making a note of where the needle is at vs. what the PCM says the engine coolant temperature is. It may turn out that there's nothing to be concerned about.