Hello all!

I was wondering if any one could give me some insight on my AC vent suddenly stop working.....the air still blows cold but mainly blow out the defrost vent. There is some slight air coming out of the rest of the vents but not like normal. When I press the mode button to redirect air to floor, front, etc..... it doesn't make a different. Does anyone have/had this problem and know the fix?

Thanks in advance!!

97C5 Owner

 

I can give you some insite hopefully enough to steer you in the correct direction.



( i'm also including a exploded view of the ducting system to refrence to)

you say its blowing out of the defrost vents mostly, that leads me to believe it is a problem with one of the following components.


1. ECC asssy (electronic climate control, thats the head unit you see in the center console)
2. mode valve (41)
3. mode valve actuator (42)
4. defrost valve(50)
or
5. defrost valve actuator(49)

although most of the AC system is electronicly controlled the valves i listed are still opperated with vacuum.
( most of the components are in the top left-hand side of the exploded view except for the ECC)

if you disconnect the vacuum line to the actuators, the zero vaccum positions should be as follows
1. mode valve - is in the middle a mix of instrument panel and floor
( if it is stuck full up will deliever to floor and full down will send to instrument panel)
2. defrost valve - is in the middle a blend to the defrost and floor
( if stuck full up air is directed to the floor and full down directs to the defrost)

i would check for an obstruction in the defrost valve then check the defrost valve actuator with a vacuum pump for full operation i believe with the conditions you listed its probable stuck down, thus a majority of the air is out of the defrost vents but some can still be felt out of the instrument vents. how ever if they both seem to be working well check with the ECC head unit an easy way to do this is to have the center console out so that you can see the box where the actuators are mounted make sure the head unit is plugged in then start the car, with it running and air blowing out of your defrost vents unplug the head unit, the vacuum actuators shoud de pressurize and return to their normal no vac values if they do definitely head unit if not a problem with the actuators or electrical wiring to them.

if you need more clairifaction just let me know


have fun



[sm=americanasmiley.gif]




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bmwdiver,

Thanks for the quick reply, I will check what you have advised and post later with the results!

Thanks again!

97C5 Owner

 

I had the same problem. My battery had leaked acid onto my vacume hoses. Had to get them all replaced. I guarantee you have a problem with your vacum hoses below your battery. Hope this helps. Mach V

 

From Mach V. Let me know if that was the problem.

 

Mach V,

Thanks very much to you and others for your imputs!!!

As I said in one of my post, I did have a battery leak and was thrilled to hear that may be my problem as it seemed to be an easy fix. I pulled the battery and the battery tray to access the vacuum hoses more easily and checked them throughly and I couldn't find any damage to the hoses.....I went steps further and pulled the RF fender to get to the T diaphram to check it.......now I don't know if this matters but the 2 hose that run to the T diaphram that connects to the vacuum cannister. The top hose I can blow into and cannot sense air going thru but the bottom one I can. Is this normal? Could that hose be clogged and is the problem? I've seen many post on this issue and have followed them all, only to have the same problem. The only one I haven't really looked into is the hose at the back of the manifold as it a b@*&h to see......

Have I missed something here?

Signed.... Still stuck in defrost mode/ and my girl is nice and cool on her side and me......well you know the story!!!

97 C5 Owner

 

Here's what fixed my issue!!! My AC is blowing colder than ever! I never thought clearing the codes would reset the actuator doors.....fuses #18 and #27 didn't do the trick, nor did disconnecting the battery!
**********************************
Check and see if you have a code in 99-HVAC B0441 H

This means the Left Actuator is out of range

I had the same problem. I found a thread that said if you have any 99-HVAC codes to clear them even if they are listed as history (that's what the H stands for) and it would fix the problem. I had code B0441 H and B0337 H I cleared them both and my problem was solved. When you clear B0441 H listen for the actuators resetting and wait until you don't hear them anymore then clear the others.......

I started my car turned on the AC and all vents blew cold air! I live in Texas so you can see I'm over joyed that it fixed my warm air (driver), cold air (passenger) issue!!!!

97C5 Owner