2002 Mercury Marquis clicking noise

2002 MERCURY MARQUIS
110,000 MILES
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ASINROLLS
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I have an intermittent clicking noise behind my dash. Sound like from behind the radio. Happens most often at start up and at deceleration. I have changed the blend door actuator recently and it is not a hot cold issue. I do still have control of vents at this time. I have noticed that once in awhile it takes a couple of seconds for air to start coming out of vents. I believe it may be an issue with the air control actuator or vacuum to it but can't find any info.
Help?
Sep 19, 2013 at 7:32 AM
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ASEMASTER6371
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this is classic of the blend door motor failing. the plastic gears are making the noise. it will totally fail at some point.

the bad news is the dash must be moved back to access it as it is on top of the hvac unit. it is about a 5-6 hour job

Roy
Sep 21, 2013 at 2:03 AM
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ASINROLLS
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Roy:

Thanks for the response. I have replaced the blend door actuator about 1,500 miles ago.. It is a lot of fun to do. I know that noise. This sounds higher in dash and less solid. Also, If I turn off system at EATC before starting car and let run a few seconds I don't have the problem. I have read that their is a similar actuator motor that controls the air vent flow direction(defrost, vent, defrost/floor) as well as a vacuum check valve. I just can't find info on how to get to them and test them.

Thank you again.

Royce
Sep 21, 2013 at 4:09 AM
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ASEMASTER6371
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there is no other electronic motor. there are vacuum acuators that operate door position but will not make the tapping noise you indicate.

does the noise change going from cold to hot??

Roy
Sep 21, 2013 at 4:17 AM
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ASINROLLS
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No. it doesn't.
Acts like a vacuum leak. For the most part only happens when car has been sitting over night(long period) and if I turn off system at EATC, start car let run for about 5 seconds it doesn't happen. Like I said I just replaced the blend door motor and observed the blend door. It moves freely. Not impossible I got bad motor but highly unlikely.
Sep 21, 2013 at 9:45 AM