I have a 2001 Sonoma ZR2. The output for the heat/ac system is "stuck" in the dash vent position. Regardless of where the control knob is positioned air only blows from the dash vents (not defrost). I removed the fascia from the dash and was able to observe that the vacuum motor arm responds when the knob position is changed, but still results in air blowing only from the dash vents. Any ideas?
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2001 Sonoma Heat/AC control problem
- Thread starter jumper09
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epiphaknee
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One of the vacuum actuators responds to changing the mode control but the defrost door does not open, hence, no defrost. The defrost actuator may still not be receiving vacuum. We don't know which actuator you were looking at. Where exactly was it located? The switch works with regards to at least one of the actuators. The defrost vent door could be jammed or broken. The defrost actuator could be bad. The vacuum hose to the defrost door/actuator could be pinched or compromised. Any hissing? Can you find the source of the hissing?
You can easily pull the defrost grill and view down into the defrost door from the outside looking in (isn't that a song?). Now, start the car and what happens? Does the defrost door by chance close shut at start-up (at vacuum load)? You'll probably need a good flash light and actually nightime is the best time to watch for this. If this is happening then the defrost door works as well as the actuator but the vacuum is not making it to the defrost actuator. Think pinched or compromised vacuum line or bad mode control.
You can easily pull the defrost grill and view down into the defrost door from the outside looking in (isn't that a song?). Now, start the car and what happens? Does the defrost door by chance close shut at start-up (at vacuum load)? You'll probably need a good flash light and actually nightime is the best time to watch for this. If this is happening then the defrost door works as well as the actuator but the vacuum is not making it to the defrost actuator. Think pinched or compromised vacuum line or bad mode control.