1991 Chevy Silverado

1991 CHEVROLET SILVERADO
15,000 MILES • V8 • 2WD • AUTOMATIC
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KURTO_15
  • MEMBER
  • 4 POSTS
My chevy 1500 makes a knocking noise coming from the passengers floor a/c area. It makes this noise for about 10-15 seconds when I turn the car on and turn it off. I know it has something to do with the a/c because when I chage it from a/c to max or something it will start or stop again for 10-15 seconds. What could this be?
Thanks
Oct 15, 2008 at 6:21 AM
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JASONRAY
  • ✓Experienced Mechanic
  • 213 POSTS
There are electronic actuators that open and close doors in your evaporator case. It sounds like a door is in a bind and as the actuator tries to open or close it, it starts bumping against whatever it's stuck on. I've heard the noise before, several times. The actuator could be at fault, as well. Depending on which one it is, (I think there's 3) you can remove it, plug it in and activate your controls and see if it still makes the noise when it's not actually moving the door. If it does, replace the actuator. Either way, that's what's happening. Some actuators can be replaced in the vehicle. Others will require the evap. case to be removed from the vehicle. Good luck...
Oct 16, 2008 at 12:34 PM
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KURTO_15
  • MEMBER
  • 4 POSTS
Thanks it was the blend door actuator and the gears inside were broke.
Thanks for all the help
Oct 16, 2008 at 1:45 PM
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JASONRAY
  • ✓Experienced Mechanic
  • 213 POSTS
You're more than welcome. I'm glad I could help. feel free to ask again if further problems arise!
Oct 19, 2008 at 10:40 AM
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