AC blowing out defogger/defroster vents - Page 2
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, AC blowing out defogger/defroster vents in Past Cadillac Vehicle Discussion; Thought I would give you all an update on this. Unfortunately, the problem is STILL present. The rinky-dink garage (don't ...
  1. #16
    EdwardP is offline Cadillac Owners Member
    Automobile(s): 1995 Sedan DeVille 4.9L V8
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    Re: AC blowing out defogger/defroster vents

    Thought I would give you all an update on this. Unfortunately, the problem is STILL present.

    The rinky-dink garage (don't know what else to call it!) that installed the AC compressor, decided to grasp at straws and told me that they believe the problem is in the electronics. They were able to get from the same used parts place as the AC compressor, on temporary loan/lease the part of the dash that consists of the speedometer/odometer/gas gauge displays, along with the climate controls on the right with the other push-button controls on the left (which I picked up for them, although I didn't think I should have had to.) They wanted to plug it in to see if that corrected the air issue, if it did not, the part would be returned.

    They then had some difficulty getting the far left vent to come out of the dash, which is still not fully back in place 100%, I could not even get it to push in the rest of the way, they likely also cracked the plastic moulding on that vent at the lower left corner - I cannot say for certain though. Then said to bring the car back on Monday as they would need it for 2-4 hours.

    I decided not to bother with them anymore and returned the part to the used parts yard - with a witness. I then went back to the garage, told them that I had returned the part and that I decided not to get it fixed. He kept asking me if I was sure, I told him yes, then also said that I would not be putting any more money into the car. I think at that point, he probably got the subtle hint that I would not be coming back.

    My uncle is going to ask a friend if he can take a look at it and possibly remove the vacuum hose (and plug it), or replace that brake release diaphragm. I told him about what had transpired with the garage yesterday.

  2. #17
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    Pull and plug that parking brake vacuum hose yourself. Nothing to it.

  3. #18
    EdwardP is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    I am very pleased to report that the problem has been resolved. It also appears to have resolved two other issues in the process.

    The door/flapper that directs the air, was not getting any vacuum.

    An earlier message suggested pulling the vacuum line from the parking brake release diaphragm under the dash - this did not work.

    A few vacuum lines under the hood had rotted over time and were replaced ($4 and change for 6' of hose at Pep Boys) by a family friend who works on municipal vehicles.

    The source of the lack-of-vacuum, was in fact, that rotted vacuum line I found dangling down the rear of the engine. After that line was replaced, he looked down behind the engine and found where the original hose had become disconnected.

    Once the new hose was connected in its place, the car was started and the cold AC air came roaring out the front vents!

    The other two problems it resolved:

    The heat is now coming out stronger from the floor vents under the dash, where it had been marginal this past winter.

    It also fixed the parking brake release, the brake now releases automatically when the car is placed into gear.

  4. #19
    noahsdad's Avatar
    noahsdad is offline Cadillac Owners Connoisseur
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    Re: AC blowing out defogger/defroster vents

    Nice work. Enjoy a comfortable Cadillac style summer!

  5. #20
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    Nice work.

  6. #21
    Chuwee's Avatar
    Chuwee is offline Cadillac Owners Fanatic
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    Re: AC blowing out defogger/defroster vents

    Hmm I was have similar problems but did not know the parking brake had any connection to my A/C issue. With me the a/c runs great but after a little while running the A/C starts blowing through the defrost vents then again after a while switches back normal. I also have a hell of a time disengaging the park brake once I set it. At least now I have something to track down thanks guys:-)

  7. #22
    2kiddad is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    I've got a variation of this problem. I have a '97 Seville SLS. A/C will blows out of my dash vents most of the time.

    Every once in awhile though, I'll start the car and air will be blowing out the defrost vents. I'll be driving along for a period of time and hit a bump in the road, go over RR tracks or pull into a drive or something and, Presto!!!, air will start blowing out the dash vents! Hit another bump or set of RR tracks, and it'll revert back to the defrost vent again! Sometimes, it'll cycle back and forth all on it's own. It's enough to drive you nuts!

    I've replaced the vacuum lines suggested in the forum. My emergency brake release works also. I've just learned to live with it, because my A/C blows cold, even thru the defrost vents. If it requires removing the dash pad, I'll continue to live with it.

    Any thoughts anybody?

  8. #23
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    I'd have a look under the dash and see if moving any electrical connectors cause the same reaction.

  9. #24
    wkearns is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    I've run into the same problem in my 97 Deville. I replaced the programmer a few years ago and things seemed pretty stable for awhile. Now it flips back and forth between the defroster and the front vents when on A/C. The hoses look good and I've checked under the dash to make sure the lines are all connected to the motors controlling the doors. On hard braking the system will suddenly shuttle back to the vents for a few moments before going back to the defroster, although on some occasions air flow comes out of the vents normally. I noticed when checking the vacuum line from the programmer to the engine that the fitting seemed to be part of an assembly on the top right side of the engine that was loose on the manifold (with the engine off). When the engine was started the assembly was rigid and would not move suggesting it was held in place by the manifold vacuum. I had one instance a while back when the engine began to race, suggesting it was the EGR valve but that seems to have been just an isolated occurrence. Still it makes me wonder whether the EGR is getting stuck and letting the manifold vacuum drop thus affecting the A/C.

    Ideas anyone?

    Bill

  10. #25
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    The EGR is monitored and will set a DTC if it sticks.

    I noticed when checking the vacuum line from the programmer to the engine that the fitting seemed to be part of an assembly on the top right side of the engine that was loose on the manifold (with the engine off). When the engine was started the assembly was rigid and would not move suggesting it was held in place by the manifold vacuum.
    I'm not exactly sure what part you are talking about, but I can't think of any part that is "held in place by the manifold vacuum". Something is not right, but based on your description, you definitely have a vacuum problem.

  11. #26
    wkearns is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    Thanks, Ranger. The area is under the black plastic shell that sits above the engine and which channels and supports the ignition wires. The specific zone is on the end of the black shell which is opposite the air intake (faces towards the front wheel on the passenger side). It looks like it's round, about 5" diameter and the tube which connects to the line leading to the vacuum motors is molded to it. I agree that it seems odd that it should move. I think my next step is to pull the black shell off and see what's amiss under there.

  12. #27
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    Black plastic shell that sits above the engine
    ?
    The intake manifold?

    The specific zone is on the end of the black shell which is opposite the air intake (faces towards the front wheel on the passenger side). It looks like it's round, about 5" diameter and the tube which connects to the line leading to the vacuum motors is molded to it.
    The manifold over pressurization valve?

  13. #28
    wkearns is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    It appears to be a plastic cover measuring about 2' x 2' which holds the ignition wires and the wires for the fuel injectors. It appears that the intake manifold is underneath the plastic cover. The cover itself doesn't appear to be the manifold. I'll have to remove it in order to get access to the area which is loose.

  14. #29
    weister42 is offline Cadillac Owners Enthusiast
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    Re: AC blowing out defogger/defroster vents

    I have a 98 Deville and I was and am still dealing with AC blowing out of the defrost vents sometimes. My situation is different... it isn't a leak, more like a blockage or something and it is somewhere right on the vacuum distributor. It'll work just fine but all the sudden it'll blow out of the defrost vents but it goes back to normal as soon as I press or wiggle the clear part of the vacuum hose. Here is a picture of what I'm talking about...


    The AC programmer





    The vacuum distributor, not sure if that's the official name





    Here is the vacuum hose connected to the engine (the one with a T-splitter), I had to replace mine cause it was all worn out





    I think 99% of our AC vent problem lies between these three areas.

  15. #30
    wkearns is offline Cadillac Owners Member
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    Re: AC blowing out defogger/defroster vents

    Ranger, you were right, it was the intake manifold.

    ----------

    Sounds like the same problem I have. Intermittent and random. Hard braking will cause the vents to cycle but there's no guarantee it will come back to the correct vents at the end.

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