New Blend Door Actuator not working properly?

BIGINDY

MEMBER
2002 CHEVROLET TAHOE
5.3L
V8
4WD
AUTOMATIC
317,000 MILES

Hot/Cool air Blend Door Actuator. Put a new actuator in. I can hear / feel actuator calibrating when you re-attach the battery after fixing it, or when you pull and replace the fuse. I can feel hot air come out during calibration, but after calibration, it goes back to cold and is unresponsive. Is this a relay problem? Is this a switch problem? The blower motor control switch works. How best to trouble shoot this?

3 Replies

STEVE W.

MECHANIC
13,443 POSTS

Well, from the description it sounds like the control head has an issue. The calibration simply applies voltage in both polarities and determines where the stops are. Under control the potentiometer tells the control head where the controller is and stops it at whatever percentage you selected. Without the feedback the control head does nothing. However, if the control head has a failure, it also won't move the motor and you get the same result.
To test the feedback side, you need a voltmeter. Go to the controller and unplug it. Set the meter to read volts and connect one probe to pin 7 (black wire) touch the other probe to pin 10 (gray wire) if the ground is good and the reference is there you should see 5-volts. If not move the probe on the black wire to a known ground. Do you have the 5-volt bias? If yes, then the next step would be to test the signal return. For that you need the control head out so you can get to pin G (light blue wire) in connector 1 and see if the position signal is there. If the 5 volts and ground tested good and the return signal, then it is the control head that is the problem. Repair or replacement are the options.

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