BigCaney:
I am having the same problem with a '94 ATX. The engine cooling fan only comes on when the AC/defroster is turned on.
Does anyone have the part number for the ECT for my '94 ATX?
Thanks,
Mike
There is more to it than just the sensor. The 94 ATX has a two speed fan circuit.
Here is the description from the 94 PCED manual:
The cooling fan system is controlled during vehicle operation by the Constant Control Relay Module (CCRM) and Powertrain Control Module (PCM) 12A650 which will energize the radiator electric motor under the following conditions:
l Radiator electric motor is turned on with reduced current for the 3.0L SHO and on at low speed for 3.0L, 3.2L SHO and 3.8L if:
a. Engine temperature is higher than normal. Radiator electric motor starts running at 102°C (215°F) and stops running at 99°C (210°F).
b. A/C clutch is engaged.
l Cooling fan will run at high speed if:
a. Engine temperature is higher than desirable and radiator electric motor has been operating at low speed. Radiator electric motor starts running at high speed at 110°C (230°F) and stops running at 107°C (224°F).
On 3.2L SHO engines, low speed radiator electric motor operation is achieved by using a dropping resistor in series with the motors.
The 3.0L/3.0L FF, 3.0L SHO and 3.8L use a dual winding radiator electric motor in which low speed fan control is achieved through the low fan control winding circuit (no dropping resistor).
The normal operation and cycling of the radiator electric motor causes the temperature gauge indicator to read between the mid-point and upper portion of the temperature gauge scale.
l The slightly higher indicator reading returns to mid-point when radiator electric motor operation begins.
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Hope the description helps. The ECT is a logical first step.
However, under what conditions did you test to reach the conclusion that the fan is not coming on? The correct procedure is to run the engine at idle speed until the temp hits the 215F threshold. This would be indicated by a stock temp guage reading at or near the high end of the NORMAL range as indicated on the guage. At this time, the fan should kick on and drop the temp back down to near the mid-point of the guage. If it is cold outside and the hood is open, there is likely to be sufficient radiant cooling from the radiator that the temperature never gets hot enough to hit the 215F threshold.
I did this test recently in my garage with the hood open with an ambient temp of around 30F. Monitoring the temp of the water outlet housing with an IR thermometer, the temp never got above 210F and the fan never kicked on. I closed the hood and covered the front of the grill with a blanket and was able to get the fan to kick on within several minutes.
YMMV.
Steve
<small>[ January 03, 2004, 08:55 AM: Message edited by: projectSHO89 ]</small>
