Date:         Sun, 8 Jul 2012 23:18:45 -0400
Reply-To:     Kim Brennan <kimbrennan@MAC.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Kim Brennan <kimbrennan@MAC.COM>
Subject:      Re: I lost my cool!!
Comments: To: J Stewart <fonman4277@COMCAST.NET>
In-Reply-To:  <2095404200.31179.1341800044720.JavaMail.root@sz0063a.westchester.pa.mail.comcast.net>
Content-type: text/plain; CHARSET=US-ASCII

A compressor can be used with either R12 or R134a.....just not at the same time. The two different refrigerants use different oils. In order to convert a system from one refrigerant to the other (usually going from R12 to R134A), the system must be flushed to remove the oil. This flushing must include all the system, and then an appropriate amount of the correct oil must then be added. In addition it is best to change the expansion valve on the evaporator. If you don't the new refrigerant will not operate at its best.

Note that there are other refrigerants, R12 and R134A are what's been used in the USA. R12 was the original used in our vans, but is no longer used in new cars and is very expensive (it's not made any more). Hence, the reason why we often convert our older vehicles to R134A.

To avoid mixing the refrigerants the USDOT mandates that different fittings be used for the different refrigerants. R12 used shrader valves. R134A uses easy on fittings (but which are different sizes for the high and low pressure sides.) Quick conversion kits often have an adapter that screws onto the shrader valve and (is supposed to) have permanent adhesive so that the adapter can't be removed.

AC technicians often have both style of adapters for their pressure gauges.


On Jul 8, 2012, at 10:14 PM, J Stewart wrote:

> Then, if that is true, the compressor Bus Depot just sold me as compatible with either R12 or R134A isn't-the label on it says "mineral oil" I'm still confused here and don't want to ruin an expensive part! Jeff Stewart ----- Original Message -----
>> On 7/8/2012 9:05 PM, Dave Mcneely wrote:
>>> Hmmm..... . The AC Pro stuff I saw today at AutoZone is R134a. The
>>> fittings for R134a and R12 are different of course. If your vehicle
>>> has not been converted, it is R12.
>> Good catch. R134a systems are required by law to have different
>> fittings, which would point to it being an unconverted R12 system.
>> R134a
>> requires a different lubricant (PAG or ester), because it won't
>> effectively carry the R12 lubricant (mineral oil) through the system.
>> The result is a ruined compressor.