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Hi.. I purchased a new used 2008 Trailblazer 3 days ago with only 35,000 miles on it (For $8100 thought that was a good deal) . Yesterday, while driving with the AC on, noticed white vapor/fume (no smell) coming out of the vents. And today, after coming home from work and parking my car in the driveway, noticed excessive amount of water dripping from under the cae. I opened the hood and also notcied excessive amount of moisture buildup on and around the tubes to and from the Accumulator (i think that's what its called? The silver cylinder thing next to the coolant reservoir). Anyway, What am I looking at here? Bad compressor? What are the step by step process to diagnose the issue. If I need to replace the compressor, is that something that I can legally do since I am guessing I have to collect the old Freon? Any help is appreciate. Thanks.

p.s. I hope the seller didn't just charge the system to sell the car, I really liked him and he seemed like an honest person .. that would really suck if he knew about the issue! the car belonged to his mother who had passed away 2 months ago.
 

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2004 chevy trailblazer_ls_ext
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175 Posts
You are correct in that the silver cylinder is called the accumulator. You can legally replace the compressor by yourself, but you will have to take the TB to a shop to have the old refrigerant removed, and have them do a vacuum test on the repaired system. While it's there have them recharge the system.
As for diagnosis, I can't really help much with that.
 

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2004 chevy trailblazer_lt
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The first thing you need to do in order to do any AC work or diagnostics is to get a set of AC gauges so you can see what the high and low side pressures are. The you have to compare those pressures against a chart that shows ambient temperature, high side pressure, and low side pressure to see if the system is properly charged, if it is undercharged, overcharged or if there is a blockage or other problem.

Once one knows what they are dealing with, they can then move onto finding a leak if the system is low on pressure and then repairing the leak, replacing a pressure switch, placing the compressor, etc.

You could be dealing with a system that is simply low on refrigerant or something more complicated like a compressor that is always engaged.

AC work does require some specialized tools, and to be "legal" you need a shop to evacuate and recover the refrigerant before doing any work. If you have a vacuum pump, you can vacuum the system down and monitor it for leaks (should hold vacuum for more than 15 minutes, although I see if it holds overnight) before proceeding to add the appropriate amount ot refrigerant by weight.
 

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Do you live in Florida by any chance? Same thing happened to me the other day when it was very humid out after a rainstorm. It did this while I was pulling air from outside and not recirculating it. I didn’t think anything of it since I figured it was just cool dry air mixing with warm moist air. But I will be following thread.
 

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2002 gmc envoy_slt
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Key question is the ac working properly as to feeling cold. My Envoy has always thrown off a lot of water under the vehicle under the Accumulator area. That is normal for this vehicle. I guess just a big vehicle and lots of heat to remove from the interior air. Never noticed a white vapor, so not sure what that means. Condensation on the Accumulator under the hood is also normal.
 

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2003 gmc envoy_sle
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I've read in other posts that over-charging can create issues. With the easier do-it-yourself re-charging cans, that come with a hose, gauge, and trigger, many people think all they have to do is squirt some Freon in. And if that doesn't work, shoot some more in, and so on. I think the over-charging trips a sensor and shuts it down to prevent an over-pressurized issue.
Like I said, that's what I read.
 

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2005 buick rainier
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Is the discharged air cold? "White vapor fume" thats an odd one there. air is passing thru the heater core and evaporator. Could be the air plenum isn't draining well enough and carrying moisture thru the vents.
 
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