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I just did some interior work this last week, including a center console replacement for my double din radio, and I happen to notice this now: My AC makes a small hiss when the engine is running, regardless if the AC is in OFF (0), or ON in any fan-speed setting. The hiss doesn't vary at all between AC fan speed settings, and I would think it's normal but what bugs me is that it also hisses when the AC **** is at 0. Maybe it's just me and it was always there and maybe I just happen to notice now, but it does irritate me to hear the AC hiss when the AC should be off. Someone please confirm if this is normal while the engine is in operation or if something might be wrong. As soon as I turn the engine off, the hiss dies out in a couple of seconds.
Extra info: I have the manual/3 button AC control unit, and my AC has been running pretty good since I got the car and it is VERY COLD, no complaints there.
How many vacuum tubes run under the dash? And where do they connect and route? I'm surprised because I was pretty careful checking what I disconnected and connected (it all seemed to be electrical plugs as I didn't spot any vacuum lines disconnected), but maybe I missed something. Thanks.
100% agree. You have to examine the vacuum control module vacuum line connections and all the vacuum actuator cans that actually move the HVAC damper doors.
The picture schematic that you see above is for the dual climate control BUT, the only difference is you only have ONE temperature door actuator where as the dual climate control system has two motors.
ALL of the C5 damper doors are vacuum controlled. You have a leak some where. Start digging!
You are CORRECT!
In fact, the dual zone system will give you DTC's for each actuator if they have issue. The Manual system absolutey does not give you ANY DTCs for failure of the single actuator. I had to figure that one out my self. There are not any DTcs for the manual actuators. Just saying..
You guys are great, thanks for the info. Where should the vacuum control module be located at? I'll start there and I'll try to find the "hiss" once I pop out the console for the 30th time this week . Looking back now it makes sense it's a vacuum leak, because the hiss disappears at WOT.
Last edited by turabo87; Aug 24, 2018 at 04:02 PM.
Guys, I found it!!! And it was totally my fault when I put the AC control unit back on the dash. I missed a vacuum connector!! I connected it back to the rear of the Temp Control **** and leak hiss is gone!! Took 15 mins. I hope this helps someone else. Thanks!!
AC operation question
. Looking back now it makes sense it's a vacuum leak, because the hiss disappears at WOT.
