ok I have 90 Geo Metro 3 cyl. It has been running fine all summer till friday when it got up to 90 (its been like inthe 100's for week straight in the beginning of August) and my engine temp started to red line ok. Opened hood and fan motor wasn't running chexked fuses all good hooked fan direct to battery runs fine so there is a bad thermostat but I dont know the location of it anyone know?

My 1st thoughts are the cooling fan relay or the "Engine coolant temp sensor for the Cooling Fan.....Not the temp sensor for the in dash gauge. That sensor is mounted by the thermostat housing. The Engine coolant temp sensor for the fan is mounted in the side of the Throttle body. Does this car have AC in it or not?

System Diagnosis

If the temperature light or gauge indicated overheating, but no boil over is detected, the gauge or light should be checked. The gauge accuracy can also be checked using a scan tool to compare the coolant temperature reading with the gauge reading.

If the engine is actually overheating, and the gauge indicates overheating, but the cooling fan is not operating, the Engine Coolant Temperature (ECT) sensor may have shifted out of calibration and should be replaced. The cooling fan relay or the Fan motor itself may also be the cause of the overheating and needs to be tested and replaced if either has failed.

If the engine is overheating and the cooling fan is operating, the cooling system should be checked.


Here's some pics that should help you rundown the problem.

Relay Box (Behind Battery - #9 Is the cooling fan relay)
http://i25.photobucket.com/albums/c83/MrBBody/RelayBox.gif

Relay Connector Terminal numbers (For Diagnosis)
http://i25.photobucket.com/albums/c83/MrBBody/RelayTerminalnumbers.gif

ECT Sensor
http://www.partsamerica.com/product_images/aap/faa/36413.jpg

Cooling Fan wiring (With AC)
http://i25.photobucket.com/albums/c83/MrBBody/GeoCoolingfanelecsetup.jpg

Cooling Fan wiring (Without AC)
http://i25.photobucket.com/albums/c83/MrBBody/CoolingfanWiringCircutNOAC.gif


Radiator fan motor does not run diagnosis chart

http://i25.photobucket.com/albums/c83/MrBBody/CoolingFandoesNOTrun.gif

Thanks for the info I checked relay it is good with good contact, what is the location of ect sensor can't seem to find uless im looking right at it. thanks

Is the "Check Engine" light on in this car while driving it? Again, does the car have AC in it or not? (Air Conditioning)....Until I know this, I dont know which chart to follow?

When you state that I checked relay it is good with good contact.....Did you follow the chart posted and run a jumper wire from terminals 2 to 4 to see if the fan came on?


If the car has NO AC in it, the part your looking for is the "Fan Thermostat Switch".....#1 in this pic.....Located by the thermostat housing. It has a "Black with a White Stripe wire and a Blue wire running to the switch.

http://www.partsamerica.com/product_images/img/nie/fs248.jpg

http://i25.photobucket.com/albums/c83/MrBBody/Sensorlocationandenginewiring.gif

no the car doesn't have ac, I put 12 v across coil on relay fan runs i put 12volts across fan, fan runs. This car is on the highway mostly so the temp doesn't really climb to much the coolant takes care of it mostly when i drive in town the temp gauge really climbs, i have fan wired to switch in dash for now but would like to fix, I'll chek temp sensor.

Found problem its the fan thermostat switch, shorted out plug with jumper fan runs let engine get hot sensor didn't show short therefor sensor is bad. Thanks for the help anyway great info.

If the car has NO AC in it, the part your looking for is the "Fan Thermostat Switch".....Located by the thermostat housing. It has a "Black with a White Stripe wire and a Blue wire running to the switch.



Found problem its the fan thermostat switch, shorted out plug with jumper fan runs let engine get hot sensor didn't show short therefor sensor is bad. Thanks for the help anyway great info.

No Problem! Just remember in the future to be specific and answer all questions by other forum members.....It saves not only you, but forum members trying to help you time and a mis-diagnosis.