A/C vents shut down after about 20 minutes

[dougwills]

I drive a 2010 3.8 Coupe that my company bought new. The last two years I have had a problem with the a/c system. When I first start the car, everything works great. Basically, no matter what setting I have the a/c on, it pumps cold air and things feel great. The display reads correctly, and life is fine.

However, I have a 45 minute commute each way, and no matter how I set the a/c, after approximately 20 minutes of driving, the vents close off. Note that the a/c is still plugging away, and the fan is still blowing at the speed it is set for. It's just that none of the air makes it out of the vents to the interior of the car. It acts very literally like someone has simply closed off/blocked the internal vents/air pipes while the system is running. I can feel a little cold air creep out of my dashboard vents or floor vents, but even though the fan is still at full speed, you can barely feel the air flow.

If I turn the a/c off (while driving or not) for 5 to 10 minutes, and then turn it back on, everything works great... for another 20 minutes or so. It just happens to be a very uncomfortable 5 to 10 minutes as I wait for the system to "reset" (or whatever it is doing), and it doesn't always work.

I have taken it to the dealer and two independent shops. Due to the fact that the vents frequently do not close when the car is not in motion, and the length of time it takes to actually occur (20 minutes is typical, but I have had it take hours before on long trips), I have had no luck getting a proper diagnostic during those three visits. I was actually encouraged by the dealer service manager to "drive around until it happens and then bring it in" so they could see it in action. Not the best response in my book, and the dealer is far enough out of my way to make this a fairly problematic attempted solution.

Anyway, my goal is to see if anyone else has had this issue, and if so, what you did to deal with it.

Thanks

 

[EdP]

I have had no luck getting a proper diagnostic during those three visits. I was actually encouraged by the dealer service manager to "drive around until it happens and then bring it in" so they could see it in action. Not the best response in my book, and the dealer is far enough out of my way to make this a fairly problematic attempted solution.

Actually, I think it is the best response. If everything is working properly it is difficult, if not impossible, to diagnose. If it is happening and you take it in (keep it running) they can see what is going on.

Could be a controller for the vents, could be a frozen coil. etc. Think about it though. You drop the car off and say, in effect, "my car is working perfectly right now so can you check it and tell me what is wrong with it?" I guess you can pay a tech $120/hr to drive it around until it happens.