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Discussion Starter · #1 ·
Problem started when motor got too hot and then ac compressor broke.
Previously the car got jump started incorrectly and 60A fuse was blown.
Replaced the compressor-dryer/condenser, began filling Freon. Compressor came on once gas entered, but cooling fan was not on. The AC switch was on.
Direct power to fan and that came on, speed controller replaced, but still no
fan. I eliminated the AC by keeping it turned off. I let engine idle til she got 230*, fan still not coming on. Turning on the AC switch does not turn the fan on, so How do I diagnose the circuitry? (ect or relay). I have power and ground at the harness side of VSC (veriable speed controller) so Iam thinking no voltage at white signal wire. How can I trick that?
 

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The white wire is a pulse mode control. From the workshop manual:

Circuit/System Description
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the engine cooling fan motor in relation to the pulse width modulated signal. The cooling fan speed can be adjusted from 10 percent to 90 percent duty cycle. 90-94 percent is considered high speed fan.

The ECM monitors the voltage on the cooling fan speed control circuit driver output. Voltage is near B+ when the driver is OFF, and near ground when the driver is ON. If the difference between the actual and expected voltage exceeds a calibrated value, a DTC will set.
 
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