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Wrenchtech
Wrenchtech, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1403
Experience:  40 years experience with ASE certification as Master Technician with L1--Repair Shop Owner
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92 chevy lumina 3.1 , fans do not come on under ...

Customer Question

92 chevy lumina 3.1 , fans do not come on under running condition , fans work with jumper wire , replaced both fan relays what is left and where is what is left to replace? what is the most common bad part for this , please help , Thank You
Submitted: 6 years ago.
Category: Chevy
Expert:  diagman replied 6 years ago.
the coolant temp sensor is the most common part that does not read the right temperature to the ecm to have the fan turn on scan computer and if you have a good scan tool you can rquest the fans to come on and if they do you know that the computer and wiring to the fan are good
Customer: replied 6 years ago.
where is the coolant temp sensor i cant find it please
Customer: replied 6 years ago.
where is the coolant temp sensor i cant find it please ,
Expert:  diagman replied 6 years ago.
BY THE THERMOSTAT HOUSING PLEASE HAT ACCEPT IF THIS HELPED
Expert:  Wrenchtech replied 6 years ago.
This is a different expert

How hot is your car actually getting?

Is it ever reaching the red zone?

Willl the fan come on with the A/C on?

Is the check engine light coming on at all?
Customer: replied 6 years ago.
How Hot red zone= the fan does come on after a real long time of idling but the guage was all the way in the red before it did , and then only one came on , the one on the driver side , the other was tested with a jumper wire to the battery and came right on . both relays under the hood fuse box were replaced and the coolant temp sensor was replaced.

fan doesnt come on when ac is on.

check engine light came on before replacing temp sensor but hasnt come on since.

so why dont both fans come on i guess is the real question i hope ?.............
Expert:  Wrenchtech replied 6 years ago.
It's very possible that your dash gauge is not real accurate and it is not getting as hot as you think it is. Ity really requires a scan tool to see what temp the computer is seeing and what it is commanding from the fans at the time.

the cooling fan isn't even programmed to come on until 223 degrees anyway.

Here is how they work


PURPOSE:

The electric Cooling Fan is used for engine and A/C condenser cooling and is controlled only by the ECM.

CIRCUIT DESCRIPTION:
Battery voltage to operate the cooling fan motor is supplied to relay by CKT 2. Ignition voltage to energize the relay is supplied to relay by CKT 650. When the ECM grounds CKT 335 the relay is energized and the cooling fan is turned "ON." When the engine is running, the ECM will turn the cooling fan "ON" if:

  • A/C is "ON."

When the engine is running, the ECM will turn the engine cooling fan "ON" for any of the following reasons:

  • Diagnostic Trouble Code (DTC) 14 is set.
  • Engine coolant temperature is 106°C (223°F) or greater.
  • A/C refrigerant pressure is 51 psi or greater with A/C selected and a Diagnostic Trouble Code (DTC) 66 is not set.

Once the cooling fan is enabled, the ECM will turn the fan "OFF" when:

  • Engine is turned "OFF."
  • Engine coolant temperature drops to 99°C (210°F) or less.
  • A/C refrigerant pressure drops to 41 psi or less with A/C selected.


You could have a relay or fuse problem to one of the relays also. The relays use a fusible link that should be coming off the starter.

Here is the wiring diagram for the circuit.


graphic
Wrenchtech, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1403
Experience: 40 years experience with ASE certification as Master Technician with L1--Repair Shop Owner
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