Corsica Cooling Fan

My cooling fan will not come on by itself. I have a new radiator fan motor, new coolant sensor, new coolant sending unit sensor, new relay, new electric plug on fan motor, new 180 thermostat, wiring is good and fuses
are good. When I put the car in diagnostic mode, the relay clicks and the fan comes on. My A/C quit working last summer and there is no pressure in the lines and clutch does not engage. I have idled the car until it got in the red (water was bubbling) and the fan still did not come on. I have a temp toggle switch (i use it sparingly)until I can figure it out. Shoot it or wait until you guys give me a new idea what could be wrong? Thanks!
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camby wrote:

GM's usually have two (or more) temp sensors - One for the fan and one for the gauge/light. The engine temp increases and the thermistor resistance decreases. When the thermistor resistance gets low enough, the ecu turns on the fan relay. Jump a temp sensor and see if the fan comes on _OR_ the gauge changes.
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You didn't say what year your Corsica is or what engine it has.
Based on a look at the controls for a '96 I would hazard a guess that your PCM might be the next suspect assuming that you have verified that the coolant temperature signal is correct and is arriving at the PCM, and that the connections at the PCM for temperature-in and fan relay control-output are intact.

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check on the firewall a fusible link could have blown. This happened to me

motor,
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