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98 3.8 Intrigue - Air from all vents


IntrigueHater
09-16-2009, 11:12 PM
Howdy all! First post, but I've spent a LOT of time on here the last couple weeks. For the last month or so, my A/C has been blowing from all the vents, and switching modes on the head unit has no effect. Every now and again it will blow all from the center, which is great in the 100+ heat in SoCal, but it doesn't last. I took it to the dealer, and they said the control unit in the dash was bad. $840 part, 2 hours labor, about $1100 OTD. eBay said $50 part and it took about 10 minutes to swap out. Problem is that the problem is still there. I tried looking up more info both online and in the Chiltons manual I have but nada. I've seen a couple of posts about the same issue, but nothing concrete. I've checked every vacuum line I cold see under the hood, and I've heard mention of a vacuum control unit, but I have no clue where it is. Any ideas? Thanks in advance!

carbon02
09-17-2009, 08:06 AM
Welcome to the forum. I'm not a fan of your username, but stay positive and people on here will help you. :-)

I've never worked on the heater before, but I believe all of the blend doors and actuators are under the dash. Under the foot panels. Your right in that the blend doors are controlled via vacuum. My guess is you've got a blend door that's actually warped itself and doesn't close all the way or your loosing vacuum to the system.

Send me an e-mail to my username. I might have some information that you'll find useful.

Your other option is to bypass the heater core under the hood by removing the hoses from the core, and jumping the connection with a tubing connection. That's fast, and gets rid of the heat, but doesn't probably allow you to have AC. If the AC's shot this is what I'd do, but if your willing to take some time, the bottom of the dash may solve the problem. Doesn't look like special tools are required, but a lot of patience!

Good Luck--
Carbon02

IntrigueHater
09-17-2009, 08:31 AM
Hey Carbon - sorry bout the username, but it's the only one I could come up with that wasn't taken. I'm not really down on my car, it's served me well for 5 years and 40K miles. But right now it's got me uber-pissed, cause my wife's safety is in jeopardy. Yesterday on her way to work the vents switched away from defrost (where it spits out most of the air) on the freeway at 75, making the windshield fog up. Not cool! Other than this latest issue, she's been a good worker bee with not a lot of issues, but this A/C things has me stumped. I'll drop you an email now. Thanks!

Some additions to my first post - car has 135K miles on it. I am extremely technically inclined and am not afraid to get my hands dirty. In fact, as long as I know what parts I'm looking for and where they're at, I'm pretty sure I can do the work myself. Bypassing the heater core is not really an option - I'd much rather fix it back to stock trim so it works normally.

IntrigueHater
09-19-2009, 08:33 AM
OK, so here's an update. I checked every vacuum line I could find and / or see. All seemed t obe in good shape and firmly connected. But there are 2 new probelm symptoms. WHen I try to use the rear defroster, I get a fast paced clicking noise form behind the dash on the right side. Kind of like a turn signal noise but faster. Also, my DRLs / auto headlights are now working intermittently. The other day they started flashing on and off, and last night they just quit while I was driving.

Could it be that the problem is actually the mystical ignition switch problem I've read about where several of the contacts are not making a good enough connection? I'm really really stumped here...

carbon02
09-21-2009, 08:50 AM
Well that mysterious clicking your hearing is the electrical relay for the rear defroster I believe. It's located up under the dash. Access might be from behind the glove box, but don't quote me on that.

If you sit in the car quietly engine off and use the keyfob to actuate the trunk, you may be able to hear the relay block clicking. I can, but then maybe I got a bad relay.

I'd believe you got an electrical problem somewhere. Check the battery to chassis ground located off the negative battery post on the battery. On the 3.5L it's located in a location where there's a lot of water and corrosion issues. Not sure on the 3.8L I had a problem with all the light's diming, headlights, dash, and interior, and it turned out to be voltage spikes, or lack of voltage due to grounding of the battery on the chassis.

It could be the mysterious ignition switch, as there's lots of symptoms, but if the switch was going I'd think the car would be loosing all voltage to the point of engine cut out. Don't know for sure, and on the 3.8 even the electrical might be different.

Alternator and Battery are in good shape?

Good Luck--

Carbon02

IntrigueHater
09-21-2009, 09:19 PM
Yep - good voltage on both, batt was just replaced a year ago, alternator was replaced a couple years ago. I figured it was the relay cause the sound is coming from the same general area that the click does when it shuts itself off.

I think the mysterry ignition issue I read about was on this forum, but I can't be sure. The posts I read said that people had the same or similar symptoms, repalced all kinds of parts, and eventually did the ignition, which fixed the problem. Apparently a couple of the contacts get "bruned" over time so they make only partial contact, causing weird things to happen, like the auto headlights to not function, and a lot of HVAC symptoms like mine. I might take the weekend and tear out my dash to haev a look see. Maybe I'll find a loose wire back there cause every connection I can see under the hood is solid.

carbon02
09-22-2009, 11:30 AM
I assume that you've seen the procedure for this that (LittleHoov) a member of the forum put together.

This was written for the 3.5L and I've never seen or sat in a 3.8L interior to confirm it's the same. I'm 99% confident it is.

You might also want to start another tread with a different thread name to engage more readers.

I know many current members have dealt with the ignition switch, but I'm not sure all of the flacky conditions that are really caused by the switch.

There has been a few success stories of cleaning the contacts of the switch, both the externals and internals, but many have also replaced the switch.

It's a somewhat expensive item to just try at $100 bucks or so with little verification of causing the problem.

Good Luck--

Carbon02

Here is the post to the instructions that LittleHoov did.
http://www.automotiveforums.com/vbulletin/showthread.php?t=736656

IntrigueHater
09-22-2009, 09:51 PM
Yeah - I saw his post and actually have it bookmarked for if I give in and just do it. $100 is not a bad price considering the alternative of buying another car, so I may try the cleaning, and if I destroy the ignition in the process I can run down and pick up a new switch. I'll try starting a new thread with an alternate title and hope the mods don't squash me for double posting. Thanks for the help!

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