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We seem to be getting outside airflow, from the front passenger floor vents, when all the AC controls are shut off (see picture). Is this normal?
Thanks for the input.
Do these vans naturally aspirate? I don't know. You only feel that if you are moving is that correct? If it is vented there should be no way to feel the air unless you are on the highway. Mind you the air outside is cold this time of year. With those settings the fan should be off.
Last edited by dberladyn; December 28th, 2018 at 2:24 PM.
Even though the blower is stopped, there's nothing to stop air from coming through the system.
Switching the selector to MAX (which recirculates cabin air) should reduce it quite a bit.
Or if you put your temperature selector in the middle somewhere, and match the temperature to what you have inside, then you won't notice the draft as much.
Also, I have noticed the AC controls go to defrost/floor mode when going up step grades. I have read there is a vacuum accumulator that is supposed to remedy this problem. Can the accumulator eventually run out vacuum if the engine has to accelerate for the period of time? Is running out of vacuum for the AC controls a common issue when going up those step grades?
Thanks again for the inputs. I learn something new about our Express every day.
Can the accumulator eventually run out vacuum if the engine has to accelerate for the period of time? Is running out of vacuum for the AC controls a common issue when going up those step grades?
In theory, yes. And my old Astro van used to do this. In practice however, this has not been an issue with my 2013 Savana/Express. Maybe the vacuum reservoir is bigger, or maybe the V8 has more suction, I don't know.
It's unlikely that the accumulator/reservoir itself is the problem. It's just a simple tank. There's no moving parts or anything else, so there's nothing that can go wrong. More likely you have some loose/leaky tubing, or the the check-valve isn't shutting properly.
If you have a vacuum gauge, you can try 'T'ing it in at various points to help you zero in on the problem.
You didn't mention what you drive, but I'm assuming you don't have a diesel which is a different system altogether.
My rig is a 2016 Express 2500 6.0 still under the bumper to bumper warranty. I am debating on whether to take it in to the dealer since the intermittent AC issue during load is not easily reproducible.
I will work on getting a vacuum gauge and posting some numbers. I've traced the vacuum line in the engine compartment, without taking things apart and it looks to be in good order.
I also took a look at the vacuum lines under the passenger side and noticed something weird. The brown tube coming from the firewall area is connected to a black tube. There is a brown tube that appears capped off. Common sence would dictate the brown tube should go with the brown tube since all the other tubes are color matched. I could be wrong though. If anyone wants to compare mine to yours, it would be greatly appreciated.Thanks in advance.
Brown tube to black tube? Or brown tube to brown tube?
Last edited by Altered4x4; December 28th, 2018 at 8:42 PM.
You definitely have a problem. All Astros had this issue, GM knew about it and never fixed it. But an Express shouldn't do it unless there's a vacuum leak.
December 28th, 2018, 2:18 PM
AC Controls - Airflow to Floor Vents?
