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Would there be any reason that my C5Z wouldn't have these vacuum hoses? I'm getting air out of each vent and it's not cycling through them when I change where I want it (face/floor/defroster). I pulled the intake manifold off and there's a vacuum hose connected to the back where the brake booster and wire clip connect, but it's only 3" long and connects to nothing.
I don't see a single vacuum line back there, or a Tee for it to go into. I pulled the battery and battery trey out to try to find any lines but didn't see any (unless it's in a wire loom). Also pulled the passenger footwell panel out from the inside of the fender, can't see anything either.
Are all the C5s vacuum actuated? or does it not need to connect to the back of the intake manifold? I'm really puzzled because I found absolutely nothing to hook up to behind the manifold when I pulled it back out.
Thanks for the response Bill. I've got a few questions to follow up.
Where do I access this reservoir? Inside the car or by removing fender wells and panels from the outside... Or thru the battery area? Because I looked for this and couldn't find it.
I have this connection (like everyone) but that small line at the bottom right goes to nothing. This is what I'm assuming is missing a connection on my car but I can't find it.
This is the back of the intake manifold area, and I can see the 90° there but I reached around and found nothing like this on mine. I used a flashlight and mirrors thinking maybe it fell and got throw further back due to gravity, but maybe I need to follow the reservoir to see where this went?
I recently did the vacuum line fix, but wanted to confirm that the vaccum line runs from the port under the MAP sensor, to the top of the check valve inside the passenger fender? For some reason, im now getting a CEL with codes Po171 running lean. :/ Only thing i can think is i disconnecting my MAP sensor and while installing the vacuum line (on a 98 it was pure hell since i refused to take off the intake manifold). i touched the terminals a few times. Maybe it made the connection ever so slightly dirty and now it cant read right? IDK. Its runs a little rough like a typical vacuum line leak but i put in a new line so it shouldnt be that.
I need some help. I have air blowing out of the defrost vent when in forward vents mode. I can change modes, but no matter what I get a little air coming from the defrost. Checked my vacuum lines and they're all good. They've clearly been replaced. All colored lines under the dash looked good. I'm getting codes for drivers actuator bo361 b0441. I cannot clear them. They'll reset but as soon as I cycle back through the codes list it shows the codes again. Can someone point me what to check next?
Even when most C5s are working 100% corretly, they will leak a little air out of the defrost vent.
It becomes particulary troublesome when the outside humidity is high and you run the inside AC temp very cold. You get a spot of condensation on the OUTSIDE of the windshield.
How much air are you seeing on the defrost vent when other vents are selected? You could find the defrost vent actuator and make sure that it is pushing or pulling the defrost damper fully shut.
I'd say you have a bad left actuator DIC B0361 Left Actuator Feedback short to GND, B0441 Left Actuator Out of Range.
The HVAC vents are controlled both electronically & by vacuum.
The direction of air flow is controlled by vacuum (defrost, foot, dash ect). The actuators control the blend doors. The mixing of hot and cold air. You say the vacuum lines have been clearly replaced. I hope whoever replaced them got the pluming correct.
The vacuum lines looking good and being good are two different things.
A check valve can look good but still can be bad.
If it was me I'd first pull the purple line coming from the vacuum control module to the black vacuum line coming from the firewall and test for vacuum at the black line. You should have 16 inches or more vacuum there and it should hold when the engine is turned off.
If the vacuum at the black line is good you have eliminated everything forward of the firewall. Next put a vacuum pump on the purple line and test that it holds. Then cycle through the modes the vacuum should drop as the vacuum motors open and close. Pump the vacuum down after each mode change and it should hold. This will verify the HVAC control and the vacuum control module is working at least for the vacuum side of things.
In my case I was getting DIC codes
B0333 Outside Air temp sensor open
B0441 Left Actuator Out of Range
B0338 Inside Air temp sensor open
B0348 Sunload temperature sensor open
B0363 Left Actuator Feedback Open
B0367 Right Actuator Feedback Open
B0446 Right Actuator Out of Range
B0361 Left Actuator Feedback short to GND
That was to many things going bad all at the same time and both actuators had been replaced a few years ago. So that lead me to believe something in the HVAC control was wrong.
Seeing the LCD back-light was getting dim also. I pulled the HVAC control module out and re-soldered the resistors to get the LCD working correctly. Then I cleaned all the pins on the module and connector. Put it back in the car and no more HVAC codes. But still had air blowing out all the vents and defroster.
I did the vacuum tests described above and found a hole in the vacuum line under the battery about an inch out from where the line coming from the IM comes out of the wire harness. Put a rubber splice in and all is working again.
Hope this helps.
Corvetkid
Originally Posted by Vetnutts
I need some help. I have air blowing out of the defrost vent when in forward vents mode. I can change modes, but no matter what I get a little air coming from the defrost. Checked my vacuum lines and they're all good. They've clearly been replaced. All colored lines under the dash looked good. I'm getting codes for drivers actuator bo361 b0441. I cannot clear them. They'll reset but as soon as I cycle back through the codes list it shows the codes again. Can someone point me what to check next?
Had the same problem with my 00! Turned out that the tube that goes to the intake was perfectly fine though, the culprit was the one that goes in to the cabin! I was lucky because it was broken just a few inches from the firewall(on motors side). Manage to reconnect a new tube and route it down to the vacuum junction. Result was BLOWING MY MIND!
It can be tough to find. I had to split several inches of harness to find the ends, only to find the reservoir in the fender doesn't hold vacuum. I plumbed mine direct from the intake to the control block. Works fine except at full throttle.
Well, I did a little more inspecting and found not one, but two HVAC lines broken! This car is a 2003 Z06 and has only 28K miles on it. I can't figure out how the hell these two were both broken? The guy I purchased the car from last year was the original owner and hardly drove it (about 1800 miles a year). Sat in his garage all year pretty much. My guess is maybe a rodent chewed threw it? Didn't touch to other wires (Thank God!) if that's what the cause was. Anyhow, I spliced on two sections of vacuum line and fired it up.. Ice cold and able to switch the vents like normal. Hopefully my fix works long term. We shall see. Here's a few pics of what I found:
Just wanted to share my experience with this issue. I checked the vacuum line inside the wire loom from under the batter tray all the way back to the manifold and it was fine. My problem was inside the fender area. The car had been sitting for over a year and some mice or rats made a nest up inside the fender and chewed through some of the vacuum lines in that area.
Here is my situation, pleas tell me if my line of thought makes sense.
I suspect the HVAC control is my culprit. I have no HVAC related codes.
When I have full AC on I get mostly air coming from the vents I choose although it is not perfect, or close. On full hot it blows from all vents, but no heat.
I pulled the black and purple vacuum lines apart and tested. I have a small leak on the black side but I think it would probably not outrun the engine vacuum. I need to run that down but not sure if it is enough to hose the whole thing.
When I tested the purple side I got some strange results. When on full defrost it holds a perfect vacuum but when I select any other vent it loses all vacuum.
If I leave the vents in the no vacuum state and shut the car off, I can pull and hold vacuum on the purple line.
I think, even though all of these parts do go bad that the likelihood of everything being bad except the controller is pretty low.
I have not tested the refrigerant in the AC compressor yet and I have a friend with a high end diagnostic tool that can fully test the head unit (we think). So I will run that and see if it can identify the vacuum manifold positions and blend actuators before I start throwing money at the problem.
I'd like to hear your thoughts and any ideas to troubleshoot the AC head unit.
Last edited by 03WhiteConv; 01-16-2020 at 10:48 PM.
Reason: Added content
You didn't specify if the cold air is cold. Is it? If going through different vents is the problem, than you most likely have a leak in the vacuum stuff. If the heat isn't working, it's probably a separate issue.
Theory is that it seems unlikely the the blend doors are broken with out throwing a code and the vacuum manifold behaves differently when it probably shouldn't. I pulled a vacuum on the underdash black line to the engine and it took about 5 minutes to loose 20 in Hg. That's not good but I think the engine vacuum could keep up with that. Not sure though, I will need to fix that leak but want to make sure I am running down the root cause first.
I also have pulled fuse 27 and reset the actuators. I could hear them cycle, smooth and quiet. I will try to get under there to see if they are cycling through the full range tomorrow night.
My gut is the controller is sending bad signals to the actuators and vacuum manifold. But my gut doesn't write the checks. 😆
Originally Posted by carlspeed
You didn't specify if the cold air is cold. Is it? If going through different vents is the problem, than you most likely have a leak in the vacuum stuff. If the heat isn't working, it's probably a separate issue.
02-20-2017, 02:14 PM
