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2003 mercury grand marquis ?
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pancho1
User
Sep 30, 2011, 1:45 PM
Post #1 of 10
(10994 views)
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2003 mercury grand marquis ?
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This vehicle I have has an EATC A/C system and it seems like the A/C is always stuck in the Auto mode. Therefore blowing air at different points, for ex. vents, then defrost, then floor. A local mechanic said it could be something not making correct contact at the control panel in the back, what do you guys think? Thanks.
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 30, 2011, 1:49 PM
Post #2 of 10
(10986 views)
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Re: 2003 mercury grand marquis ?
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That is not how the auto mode works. You have an issue with the mode door that has to be diagnosed and resolved.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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pancho1
User
Sep 30, 2011, 1:55 PM
Post #3 of 10
(10980 views)
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Re: 2003 mercury grand marquis ?
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So it's the mode door, can you tell me where that is? And how would I diagnose it?
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 30, 2011, 2:03 PM
Post #4 of 10
(10975 views)
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Re: 2003 mercury grand marquis ?
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The mode selection is done through a series of air doors that are operated by vacuum. When there is either a partial or total loss of vacuum, the system will default to either defrost or on some vehicles, heat. Acceleration can also have an effect on the doors for the same reason.
Look under the hood for a small black plastic hose coming through the firewall. Follow it to the vacuum source looking for any breaks, cracks or leaks. Also follow any other lines that branch off because they may go to a vacuum reservoir (storage tank) and a leak there will cause the same problem. Using a vacuum gauge to determine if you have full vacuum at any given point is the best way to find it. You can cut into the line anywhere and splice it back together with a piece of vacuum hose. Find the broken line, you found your problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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pancho1
User
Sep 30, 2011, 2:09 PM
Post #5 of 10
(10970 views)
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Re: 2003 mercury grand marquis ?
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Thanks Hammer Time, I'll have to check that out, any other suggestions from anybody else would be greatly appreciated.
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Discretesignals
Ultimate Carjunky
/ Moderator
Sep 30, 2011, 8:13 PM
Post #6 of 10
(10943 views)
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Re: 2003 mercury grand marquis ?
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This is also another possibility.
They also had a lot of problems with the EATC control panel solenoids leaking inside the panel. Dealers would usually replace the panel, but someone has figured out how to replace the little o-rings in the solenoids to fix the leaks.
Google "EATC orings". There are a couple of sites that have information on repairing yourself and saving you bookoo dollars. If you don't feel like repairing it, you can always fork out $700 for a new one or take your chances with a junk yard one.
The four solenoid plungers in the lid half of the panel can be re o ringed:
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Sep 30, 2011, 8:22 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 1, 2011, 10:29 AM
Post #8 of 10
(10912 views)
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Re: 2003 mercury grand marquis ?
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Picture of what, a plastic line?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Oct 1, 2011, 11:22 AM
Post #9 of 10
(10908 views)
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Re: 2003 mercury grand marquis ?
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Instead of ripping the car apart looking for a vacuum leak, have your mechanic connect a smoke machine up to the vacuum supply line at the manifold. Make sure they turn the vacuum check valve around when smoking out the system. You'll find the leak(s) a lot faster. Pull the EATC panel out and check for leaks in the panel also. We had one a month ago and thats how we found out the solenoids rings were leaking. You can also pull the vacuum harness connector off the back of the EATC panel and smoke out each individual vacuum actuator.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Oct 1, 2011, 11:26 AM)
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goat794
New User
Jan 24, 2012, 1:18 PM
Post #10 of 10
(10552 views)
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Re: 2003 mercury grand marquis ?
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Thanks mr discretesignals for your help!!!! i pulled my atc control out of my 2003 mercury grand marquis and replaced the o rings on all 4 plungers with new o rings from graingers and the system works just like new.. outstanding thanks again. the repair cost me $7.50, the grainger part number is 1REC2 and comes with 100 o rings just fyi .again thanks so much for your time and help steve
(This post was edited by goat794 on Jan 24, 2012, 1:21 PM)
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