2006 Cobalt 2.2 radiator fan doesn't come on. Any help diagnosing would be appreciated.
Radiator fan will not start automatically even when temperature is above 200F. The temp. sensor displays the correct temp. and if disconnected it displays -48F and the fan runs. Fan relay is good. Can run fan from either relay. Freon is bleed from AC so can force it to start by turning on AC. It tests as if the #2 relay has an open ground on the coil side. Can't get access on #I relay to check it.
not the answer you want but you need to get to the other relay and inspect.
Have tested the relays out of the car and swapped out with one new one in both positions. No change. I don't have a wiring diagram for the coil side of the relays. I have 12V to coil side of the relays but the circuit is open somewhere on the ground side after the coil. Not sure what switch closes the coil circuit at temperature (ECM?). I think the set points are 190 for low speed fan and 195 for high speed fan. I don't have wiring diagram. Could the temperature sensor or a connection to it being faulty cause the fan not to engage yet provide the correct engine temperature. This started with a stuck thermostat a couple weeks ago and the fan was working fine so I wonder if I did something inadvertently to the fan control circuit.
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