How do you check engine cooling fan relay

the usual suspects are:
stuck shut thermostat
clogged raiator
dead water pump
low coolant level
it's sunday, rovers don't work on sunday.
Then again, maybe its wednesday, rovers take half a day then.

natural for engine temp to rise in Traffic - Until Themostat opens ) cooling fan sensor kicks on fan . But Antifreeze is not just a Cold weather item . Coolant is Absolutely Necessary for Hot Days . You must be full to recovery bottle setting of cold when checked prior to start up . Coolant for your make / model is Reddish - Pink colour and should have a reading of -25 thats negative 25 degrees the Lower the Better even - 50 .. Why ?? - 50 is 50 %% antifreeze / Coolant Concentrate MIX Gives Hot weather cooling Ability or very cold weather starting / winter HEAT .

Wait till the engine is cold, remove the radiator cap, start engine and look for coolant gushing out of radiator or a lot of bubbles, its possible you have a blown head gasket.

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.

It is normal for the A/C air to warm up a little when stopped. Less airflow thru the condensor. It is normal for the engine temperature gage to rise up to about the 80% mark on its scale before the cooling fan kicks on. The gage will also show about the same reading on the first start of the day, until the thermostat opens.

If the fan(s) are not working properly the A/C air and engine temperature will rise. If you have a belt driven clutch fan, the clutch may be worn out. All cooling fans kinda sound like miniature jet engines when its hot out, more so when the A/C is on. Replacing the clutch is all you can do for a belt driven fan. Electric fans are more complicated....
Check all main power electrical connections first.... Electric Fan(s) not working, Checking the fan(s), relay, fuse and engine temperature sensor's.
Verify that the fans work by unplugging them and run jumper wires to the fan(s) from the battery. If they run, your problem lies elsewhere. If either does not run, it's the motor.
Next thing to check is for power at the fan connectors. You have to be cautious doing this because the engine needs to be running and warm if not almost hot, and the A/C also needs to be on. (Both must be on and running for the duration of this checklist.) The A/C fan is on the passenger side and should come on almost the instant the A/C is turned on. It is also the secondary engine cooling fan and should cycle on and off in relation to engine temperature. Use a test light to probe the two wires on each fan. If you find power the fan motor(s) is/are probably bad. If there is no power to fans, roll up your sleeves!

The temperature switch is usually located above the oil filter. If the dash gage is working, its probably OK. Next is the Fan Control Temperature Sensor, located IN or CLOSE to the thermostat housing. You will find out if it is working later is this checklist. I just wanted you to know where it is. Next is the relays and fuse's. Usually located in the engine compartment on the passenger side power distribution box. You will need to remove anything over the cover to open it. If the fuses are OK, tap on the relays or pull them out and push back in. If the fans are still not running, pull a relay and probe the socket terminals for power. Two or three of the terminals should have power, usually criss-cross from each other. Two are hot battery power, and the third is the "signal" voltage which triggers the relay to send 12V battery power to the fan. This signal voltage comes from the sensor at the thermostat. If only two terminal's have power, then I would replace the thermostat sensor if not both sensors.

Hope this is clear as mud! and helps! Please let me know what you find.

will try to help. have you made a visual inspection,while car has been driven and stopped,w/engine running, is engine fan running? it cools the motor at stop lights and at idle speed after car has been driven and needs additional help cooling the motor. the thermostat in engine controls the engine temerature, if it [temp. guage moves from 200 and below] the thermostats working. check main fuse box under the hood for blown cooling fan fuse,or a bad cooling fan relay. hope this helps, and as always, thank you for choosing fixya.com.........if you need further assistance, please repost your question, and we'll be happy to assist you!!

The next thing to do is to observe the car as it idles for 10 minutes to ensure the electric radiator fan is coming on if not replace the fan relay if that doesn't work replace the coolant temp. sensor that activates the relay that activates the fan after that ti can only be the fan itself that is if the fan is not coming on.

If the motor does not sense it is getting too hot, the fans will not come on. When it reaches a certain temp, they will come on. If you are having problems with over heating, and the fans are not coming on, I would suspect the fan temp sensor, or the PCM.

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

The water temp sensor is located near the thermostat housing. This sensor is what tells the ECM to turn the fan on/off. The water temp sending unit is located near the same area. You know you have the correct sensor is because the water temp sensor has a 2 prong plug. The water temp sending unit only has 1 prong.