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Hello, i am having an issue with my a/c on my 2011 ram 3500. It works fine for about 30 mins to an hour. Then all the air stops blowing. Does not come out any of the vents but you can still hear the blower motor running. Shut off the truck, sit for a few min then start it back up and it works fine agian. It has the dual zone with the automatic setting. Any idea what is going on , oh yeah and it doesnt matter if you switch it to any other venting options it still doesn't blow out any air.
 

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'18 RAM 3500 4WD Tradesman 6.4
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How about air intake options? Does running the system in recirc mode or outside air mode make any difference?
 

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'18 RAM 3500 4WD Tradesman 6.4
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Huh.
If the blower is still running, but there's no air coming out of anywhere, regardless of how you set the distribution controls, there has to be something blocking the flow somewhere.

When it is running as expected, do all the distribution controls work as they should?
Does the fresh/recirc baffle actually work to reliably switch the air intake from outside to inside?
It's a puzzle for sure. I did have similar symptoms once on a Subaru, when the baffle on the intake side came adrift and blocked air from entering the blower. Naturally that prevented anything from coming out of any of the vents. But it didn't resolve itself after shutting the car off like yours is doing.
I had a situation in an old Toyota once when debris from an old mouse nest was hung up in the duct work but would move around from time to time, and that caused intermittent stoppages similar to what you describe, but not the same, and not as predictable at all.


It sounds like a diversion control gate is closing off somewhere after it's been running a while, and then it resets to normal defaults again after shutting the system down, but that's a total guess. A single failure on one gate that causes stoppage of all air flow would most likely be on the intake side, but could be the first gate on the output side. Otherwise more than one gate would have to fail to give the symptoms you describe.

Tricky.


The only other straw I can clutch at is the possibility that while the blower motor sounds as if it's running as it should, it's not always driving the fan/turbine for some reason, like slipping on its drive shaft or something when the motor is warmed up, but then it grips again after it cools down a bit. But that's just a wild-ass guess and I've never known that to happen. If the blower fan is always turning, and it's either starved of air on the intake side, or unable to vent the air due to a blockage on the output side, there will often be a change in the sound it makes. When the system quits moving air at all, have you noticed any difference in the way the blower/motor sounds compared to how it sounds when it's working as advertised?


What you need is a highly trained ferret that you turn loose in the ductwork and it runs around in there checking everything out for you, then returns with a full report. Failing that, you may have some tedious work accessing all the components ahead of you.
 
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