Test "C" (Blower Motor Runs At High Speed In All Settings)

WARNING: This page is about a different car, the 1996 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

Check EATC System

Test EATC system operation. See EATC SYSTEM TEST under TESTING. Repair as necessary. If system tests okay, go to next step.

Check Blower Motor Operation

Start engine. Select MAX A/C. Rotate blower motor thumbwheel back and forth between highest and lowest speed settings. If blower motor operates at high speed only, go to next step. If blower motor speed varies, blower motor is functioning properly at this time.

Check Voltage Input At Brown/Orange Wire Terminal Of Blower Speed Controller (BSC)

Turn ignition off. Disconnect BSC connector. Start engine. Select MAX A/C. Rotate blower motor thumbwheel to lowest speed setting. Move thumbwheel back and forth between highest and lowest speed settings, and measure voltage between terminals No. 2 (Brown/Orange wire) and No. 5 (Black wire) of BSC connector.
Voltage should be zero volts in highest speed setting and 1-2 volts in all other speed settings. If voltage is as specified, go to step 6). If voltage is always zero volts, go to next step. If voltage is always more than 2 volts, replace EATC module (control panel).

Check Voltage Output At EATC Module

Turn ignition off. Reconnect BSC connector. Start engine. Select MAX A/C. Rotate blower motor thumbwheel to medium speed setting. Measure voltage between ground and terminal No. 7 (Brown/Orange wire) of EATC module connector (backprobe terminal). If voltage is 1-2 volts, repair Brown/Orange wire. If voltage is not 1-2 volts, replace EATC module (control panel).

Check Voltage Input At White/Pink Wire Terminal Of BSC

Set blower motor thumbwheel in any speed setting except high. Measure voltage between terminals No. 3 (White/Pink wire) and No. 5 (Black wire) of BSC connector. If voltage is zero volts, replace BSC. If voltage is not zero volts, replace EATC module (control panel).