[ale] [WAY OT] WARNING - diy car ac recharge kits can be dangerous

[Ron Frazier (ALE)]

On 8/15/2013 10:14 PM, Phil Turmel wrote:
> On 08/15/2013 06:17 PM, Ron Frazier (ALE) wrote:
>    
>> Hi all,
>>
>> I just wanted to follow up and tell you how things worked out and share some more info.
>>
>> I picked up the car and talked to the 2nd mechanic at the shop who is very familiar with ac systems.  He said:
>>
>> * It is definitely possible to overcharge the system with those cans, and it's highly likely that is what I did.
>>
>> * The little gauge on the can does little to tell you the state of your system.
>>
>> * He sees this a good bit with other customers who've done the same thing.
>>
>> * If you overcharge, the low side pressure can stay the same and the high side pressure will go up.  The gauge on the can only shows the low side pressure.
>>
>> * The system has a high pressure cutout switch that is supposed to prevent failure.  The switch is always on under normal circumstances to allow the compressor to run.  In my case, the high pressure cutout switch did its job.  But, the switch can fail on, in which case, excessive pressure can develop.
>>
>> * He has seen a case where someone overcharged a system and where the high pressure cutout switch had failed on.  The compressor exploded.  Fortunately, then mechanic had not yet opened the hood and got close to the compressor when it went.  He said the result was NOT pretty.
>>
>> (Ron talking again.)
>>
>> My opinion, for what it's worth, is that it's unlikely that the high pressure cutout will fail.  But, obviously, it can happen.  That, combined with erroneous maintenance, can be catastrophic.
>>
>> The mechanic checked my wife's car (for free) and the pressures in it's system are fine.  In her car's particular case, it's about 30 PSI on the the low side and about 150 PSI on the high side.
>>
>> So, that totally settles it.  I will NOT be using the DIY  ac recharge cans again.
>>
>> My little lesson in air conditioning physics (and marketing) only cost me $ 102.  I'm glad it wasn't lots more.
>>      
> Vehicle air-conditioning is one of those super-expensive repair items
> that I can't stand to pay for.  Especially since I still buy old cars
> that rarely have working A/C.
>
> At the moment, bulk containers of r-134a are relatively cheap (I got
> 30lb at Sam's for ~$90 a couple months ago).  As it has no chlorine, it
> has minimal ozone impact, and remains unregulated for personal use.
>
> With bulk refrigerant, a spring scale, and a $100 commercial gage/hose
> set, you can cheaply handle minor leaks for multiple cars for multiple
> years.
>
> http://www.samsclub.com/sams/johnsen-s-r-134a-refrigerant-cylinder-30-lbs/156595.ip
> http://www.mscdirect.com/product/76933472
>
> For more serious leaks, a sniffer and vacuum pump are needed.  But then
> you can just buy parts.  Repair parts are *way* cheaper than the labor
> charges for this kind of work.
>
> http://www.grainger.com/Grainger/SUPERCOOL-Vacuum-Pump-4LTW8
> http://www.grainger.com/Grainger/TEST-PRODUCTS-INTL-Leak-Detector-3KRF5
>
> Would come close to paying for themselves the first time you replaced a
> compressor.  I've recouped the cost of my tools several times over.
>
> Phil
>
>    

The container you're talking about is functionally no different from the 
can that I had.  Based on what I read, the only safe way to ensure the 
proper amount of refrigerant is in the system is to vacuum it down and 
put the refrigerant in by weight.  Also, you have to make sure the 
compressor has adequate oil in it.

Are you saying that there is a safe way to "top off" without 
overcharging and potentially creating a dangerous situation and without 
doing a full vacuum down?  Obviously, monitoring the low side pressure 
is not adequate.

On a side note, don't you have to have to have a business license to buy 
from msc or grainger?

Sincerely,

Ron


-- 

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Ron Frazier
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