A/C blowing thru defroster

[Leejr57]

My wife's 95 SE is blowing the a/c thru the defroster not the dash vents. Are these controlled by vacuum or electric?

[Archon]

I believe that is vacuum controlled, and is often caused by a disconnected or loose fitting at the vacuum reservoir. Look under the hood, toward the center of the car from the brake booster for that connection on the firewall.

[Echo SSEI]

Other possibility is one or more collapsed nipples on your HVAC connector underneath the passenger side of your dash.

Here is my write up for to fix that for under $2.00.

If you have cold and hot air, but it only blows out the floor vents, then their is a loss or blockage of vacuum. Which vents air comes from is vacuum controlled. A leak in the reservoir tank or line from the resrvoir tank (black plastic blimp-looking tank located in front of the passenger side front tire), or a leak in the fittings or vacuum feed (small purple-violet vacuum line from a T-connector up by the alternator and then through the firewall into the HVAC programmer under the passenger side dash) or a collapse of the nipple(s) in the connector attached to the programmer case is usually the problem.

If it is a nipple collapse at the HVAC connector, here are the nipple fix procedures I used:

The violet colored line shown in the pics below is the vacuum supply line for the HVAC system. It runs though your firewall, into a harness cover (with other wires) where it t's off to a black vacuum line that connects to the vacuum storage tank, in front of your passenger side wheel, underneath the car. A leak in this line or storage tank (black plastic pill looking tank about 8 inches long) may cause the system to take a long time to store up enough vacuum to operate your system. You may need to check the tank and the vacuum connector for cracks/splits/problems.

On to the "nipple" fix. First remove the plastic panel that is way underneath the dash, on the passenger side. Move the passenger seat back as far as it can go. Lay on your back and look underneath the dash. You should see a bunch of multi colored vacuum tubes going into a clear connector that is part of a black plastic box (the box is your HVAC programmer).



There are two bolts that hold the plastic box together. One on the middle front of the box and one on the bottom. You may not see the middle one, but you can undo it by feel. Get a flashlight and look at the box to get an idea of where the bolts are and what they are like. Loosen the bolts (you do not have to take them completely out) and use the flat blade of a screwdriver to pry the box open (like a clam shell). Keep loosening the bolts until you can remove/slide the clear (and black) piece that the multi-colored lines are going to out of the box. Also, there is no need to undo the nut from the clear plastic connector circled in the pic. There are lines on the other side of the piece as well, but they are different colors. Note which color lines up with which other color (make a diagram if needed).

The lines lead to another clear connector inside the box that looks like this, but you don't need to take the box apart and get to this piece for the fix. You only need to cut the lines at the connector itself.



Once the piece is dangling free from the box, you simply cut each vacuum line (do it one at a time or use your diagram of the colors) at the connector on both sides. Get some new vacuum tubing (I took a small piece from one of the lines I cut to NAPA, to insure I got tubing that was tight, but not too tight.) and rejoin/reconnect the lines, in correct order, matching the two different colors (from the diagram you made) using the new tubing. I used a little WD-40 to help me slide the vacuum lines into the tubing.

Re-route the connected tubes through the hole in the black box where the clear/black connector used to be, retighten the bolts on the black box, enjoy air from center vents.

The finished product would look similar to this photo. I only used about an inch of new tubing on mine instead of the several inches shown in this pic.



More pics showing the programmer and connector for further reference

[Leejr57]

Thanks for the quick response. I'll check it out when she gets home from work, and let you know what I find.

[anwisdom]

AHHHH,
It was literally 108 degrees here in Oklahoma City. I did what Echo said last night and.....AHHHHH. No more clear vent deflectors for me! Thanks echo!

[Leejr57]

It wasn't as bad as I thought, the vacuum hose from the intake manifold has rotted off at the black box on the firewall. I not only fixed the A/C problem, it also "fixed" the check engine light coming on!

[bigpaul2600]

I just want to make sure I am reading this correctly. The point is to get rid of the vacuum connector (little black box) and connect the lines directly to each other?

[Echo SSEI]

I just want to make sure I am reading this correctly. The point is to get rid of the vacuum connector (little black box) and connect the lines directly to each other?

100% Correct! The connector holes themselves are what collapses and causes the issues.
This connector gets repalced by small tubing and this connector gets tossed away

[mrbambihunter]

I have the same problem on my 99 Bonneville, would this procedure be the same ?

[michaelbsc]

I have the same problem on my 99 Bonneville, would this procedure be the same ?

I'm wondering if this is also the problem I have with the diverter "wandering" from the defrost to the dashboard vents. It almost seems random where the cold air is going to blow.

[willwren]

Please don't dig up 3 year old posts. It causes confusion, and our knowledge and experience may have progressed since then, or the information may have been more recently refined.

Start a new post (or continue in your original) and LINK back to the older post.