How long can I leave AC open w/o imperiling Drier (#$%^! Apartment!)
 

At 11:30 PM I finally had my new compressor bolted in and I was getting ready to seal up the sytem and pull a vacuum. Suddenly apartment security drove up and told me that one of the neighbors was upset and couldnt sleep because of my noise.
What? What is this world coming to? Why can't I bang, drop tools, talk to myself loudly, (Come on Rich, you can do it..hang in there...good job Richie...)and run in and out of my unit to get tools, slamming doors at midnite? Just because someone has to sleep and work for a living? Haven't people heard of Sleep Deprivation? Don't poeple know how to take naps at Traffic Lights because you know you will be awaken by the driver behind you when he blares his horn?(Just kidding, i was very embrassed and apologized)
Meanwhile my System is open, at least until noon today. My drier will have been exposed to atmosphere for maybe 14 hours. Do I have to replace?

I would, not sure which car you are working on but can't imagine you are talking to far north of $50. Pretty good insurance against keeping the neighbors awake another night in the future.

It's not a cardinal rule but a best practice - like replacing valve stems when you get new tires. Somethings you just do.

a drier does just that, it dries. and there is a LOT of moisture in the atmosphere! anything over a few minutes, and you pretty much have hosed the drier.
John

Best to leave the vacuum pump running all night. :D

I am not convinced that a drier can be vacuumed out. it chemically absorbs the moisture, so removal would be difficult if not impossible. best to replace the drier and only open it after everything else is installed in the system.
John

When a dryer has been exposed for an hour, let alone 14, it's garbage. Replace it.

How does the dryer work?

It uses a desiccant sack that any absorbs water that comes near it. http://en.wikipedia.org/wiki/Desiccant

Wouldn't the dessicant get saturated after a short time, and then be useless? Somehow the dessicant dries out too...how?

Just wondering.

If it dried, it would be reusable but it doesn't so it's not. It absorbs moisture and holds it. Once it's saturated, it can't absorb any more. That's why it becomes useless once it absorbs moisture. Laying open in the cool humidity of the night air, it will be garbage in less than an hour. look at a new one in the box. It has plastic caps covering the ports for a reason. It would absorb moisture while sitting in the box on a shelf at some parts warehouse and be garbage even before it's sold.

There are ways to recover the dessicant so it can be re-used. I have read about this being done on large commericial A/C units. The dessicant is heated up which drives the moisture out of it. I have never heard this being done with the drier from a car A/C unit. At $30 to $40 bucks a pop, they are cheap enough to replace.

TimK

If it was exposed to an ongiong dosage of moisture,yes it would saturate (it does not "dry out") but remember, we are dealing with a sealed system. It is intended as a sort of one time shot to get the moisture out upon initial seal up and after servicing. It is usually a good idea to replace it every time you open the system for service. These sytems are very sensitive to airborne particulates and moisture, any time I open a line, I clean it thoroughly first, have a few heavy wall small baggies handy and some zip ties, as soon as that line gets opened the baggie gets ziptied over the end of it and sealed airtight (or close to) with some tape on each exposed opening.
In his case, it doesn't sound like he sealed the ends, so he would definitely need to replace the drier, and should probably now have the system flushed, (you'd be amazed how much dust can get in there quickly) & once it hits the compressor....