help! rad fan will not turn off

[FIERO-JOE]

i have a problem.. when i turn off the fiero.. the rad fan continues to run.. none stop..
until the batt runs dry.. the only way to stop this is to unplug the rad fan
 im not sure what changed to make this happen??? i did nothing.
could it be the rad relay?? the thermostat???
any ideas and possible fixes would be great help..
thanks all
joe

[aaron88]

I have heard of this happening before.  Something to do with old wiring and or bad grounding.

Basically you need to track it backwards.
The fan only runs if it has power
Power is fed though the relay from a fusible link
The relay is closed only when there is power through the relay coil (pin 85 and 86)
The relay is hot all the time (switched grounding)
A temperature sensor switch in the block closes when hot, your coolant fan AC pressure switch closes when the pressure gets over 280psi (AC cars only) or your AC control is on with power on.
These switches close the circuit on the ground side of the distribution.  Therefore if you have a bad switch your fan will run all the time.
If you have a bad wire coming from the coil side of the relay anywhere to ground your fan will run all the time.
If any of your switches are bad your fan will run all the time.
If your controls for your AC (if equipped) are grounding your fan will run all the time.

Order of operations

Warning – do not pun an ohm meter on a powered circuit.  Make sure circuit is not energized.

Check your Coolant Temperature Switch in your block with an ohm meter from the pin in the back to your engine block while the engine is cold (pull of the wire first so it is not connected).  If you read no resistance your sensor is bad.  Replace and check your fan operation.  If you read infinite resistance your switch is somewhat operational.  I won’t get into checking the operational range.

Repeat this process with you’re A/C pressure switch.

If you still have a problem, disconnect both ends of your wire from the switches and your relay (Just Pin 85 or 86, Whichever is on the grounding side of the relay).  And check for resistance to your body grounds.  If it’s not infinite you have a wire issue.  Track the wire to find where it is exposed and fix or replace.

I won’t get into checking your A/C controls unless you still have a problem.

Aaron

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[FIERO-JOE]

wow thanks...
i charged the battery again.. and unplugged the rad fan.. BUT the battery was still dead this morning.. so what ever is powering the fan is still running and i dont knwo where that is to turn it off.. unless i unplug the battery terminal..
thanks for the info.. i will hack at it this week,,
joe

[FIERO-JOE]

got the news.. its working now and its great..

It was the switch on the AC compressor.. it broke and caused the relay to stay open killing the battery..
and the altinator was not working properly// so it was unable to charge the battery as i drove but well enought to keep the car going with little else running...so i was able to drive it.. but needed to boost it at any stop..
thanks again guys..
joe