I have changed the fuse and relay. The fan should come on when I turn ac on max, but it does not. I think it may be the coolant temperature sensor,but not sure. Also the ac quit working too when the fan went out. Please help
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check cooling fans fuse and relay.bad engine coolant temperature sensor will cause coolant fans not to turn on.if AC system not working with no refrigerant in the system cooling fans wont turn on when you turn on the AC.problem in PCM will cause fans not to turn on.
if engine at long stand still,the engine temperature will rise about 190 degrees the cooling fan suppose to automaticaly turn on when coolant temperature sensor get hot it cause its resistance decrease causing pcm to send power to coolant fan relays and cooling fans, when you turn on AC the cooling fans suppose to turn on to cool down AC CONDENSOR, IF NOT AC WONT WORK COOLING FAN COOLS DOWN REFRIGERANT SO IT CAN RECYCLE THROUGH THE SYSTEM AGAIN.your cooling is suppose to turn on when engine at a sit still if vechicle not moving as coolant temperature rises at a set point the cooling fans will turn on cool down engine.cooling fans dont turn on when you first cold stsrt vechicle unless you have AC SWITCH ON.if cooling fans dont turn on when vechicle at a long stand still or moving along slow traffic.if coolant temperature sensor been replaced and fuses and relays okay have dealership check see if pcm driver circuit working faulty pcm will cause cooling fans not to turn on.
REPLACE THERMOSTAT.ITS STICKING CLOSE TO KEEP COOLANT FROM CIRCULATING THROUGH ENGINE AND RADIATOR. THE FANS SHOULD COME ON WHEN VECHICLE SETTING AT A LONG IDLE.THE COOLANT TEMPERATURE SENSOR GET TO CERTAIN TEMPERATURE WHICH WILL COMPLETE CIRCUIT PCM SEND POWER TO COOLANT SENSOR THEN TO COOLANT FANS RELAYS AND FANS.IF VECHICLE OVER HEATING WHILE MOVING THERMOSTAT FAULTY.IF YOU TURN AC AND COOLANT FANS DONT RUN CHECK COOLANT FANS FUSE AND RELAY.IF COOLING FANS DONT TURN ON WITH AIR CONDITIONER ON EITHER COOLANT TEMPERATURE SENSOR FAULTY OR PCM FAULTY.IF ALL LOOKS GOOD.IF ENGINE OIL LOOKS LIKE MILK SHAKE.YOU HAVE BLOWN HEAD GASKET.
IF CAR OVERHEATING AT STANDSTILL OR IDLING IN A LONG TRAFFIC LINE.COOLANT FAN NOT TURNING ON.MORE LIKELY COOLANT TEMPERATURE SENSOR NOT WORKING.USE A SCANNER TO CHECK COOLANT TEMPERATURE WHEN ENGINE HOT.IF TEMPERATURE READ LOW COOLANT TEMP.SENSOR BAD.IF SENSOR OKAY.CHECK COOLANT FAN FUSE AND RELAY.ALSO HOTWIRE FAN TO SEE IF FAN MOTOR WORKING.IF NO REPLACE FAN MOTOR.IF FAN MOTOR GOOD FUSE AND RELAY COOLANT FAN MOTOR WIRE CONNECTOR IS DAMAGED OR HAS BROKEN WIRE.
CHECK COOLANT LEVEL TO MAKE SURE NOT LOW.IF ALL LOOKS GOOD.CRANK ENGINE LET IDLE FEW MINUTES TURN ON AC MAX LEVEL TO SEE IF COOLANT FANS COMING ON.IF NO CHECK COOLANT FANS FUSE AND RELAYS.IF COOLANTS FANS COME ON WHILE ENGINE OVERHEATING THERMOSTAT BAD.IF ENGINE OVERHEATING FANS NOT COMING ON YOUR COOLANT TEMPERATURE SENSOR FAULTY.
WELL TURN ON AC MAX COLD HIGH TO SEE IF COOLANT FANS TURN ON.IF NOT YOUR REFRIGERANT SO LOW THAT THE AC REFRIGERANT PRESSURE SENSOR WONT CLOSE CIRCUIT TO TURN ON COOLING FANS.MEANING YOU NEED HAVE AC CHECKED AND CHARGED.ALSO CHECK COMPRESSOR FOR POWER IF NOT YOU HAVE BLOWED FUSE OR BAD RELAY.IF FUSE AND RELAY GOOD YOUR AC COMPRESSOR CLUTCH COIL OPEN OR THE AC CONTROL SWITCH IS BAD.IF COMPRESSOR IS RUNNING WHEN YOU TURN ON AC YOUR AIR TEMPERATURE ACTUATOR NOT WORKING.
Check relays (usually un.derhood) first See owner manual for location. Then check engine coolant temperature sensor. If it's not providing high temp signal, the fans won't come on. However, the fan usually comes on when a/c is engaged. Leaing towards relays
Cooling Fan Temp Sensor is the First thing You Check (with what you have described) Cooling Fan Should ALways come On When The A/C is turned On as A/C Adds A Load to Engine, If Temp Sensor is Faulty it Will Not Give GROUND Signal to ECM >For COOLING FAN >RELAY to Give ground and turn ON The Fan.
There ARE 2 temp Sensors that Serve Different Purposes 1 is for Dash READING GAGE & Or TEMP LIGHT the Other is For ECM or Fan Relay (SAME Thing) you Said>""can disconnect the sensor and fan continues to run" < This Leads me to think you Changed the Wrong One. Not Questioning your Skills Just Here to Help.
TEMP SENSOR FOR 3.1L V6 is Located upper RH rear of engine compartment, near exhaust system. Temp SENSOR for 2.3L Engine is Located in LH rear of engine compartment. I Hope this Helps Lead you to a NON-OVERHEATING Pontiac.
Good Luck and Have A Great Evening. rejakwilson