You evacuate the system with a proper refrigerant recycling pump. A vacuum is created within which will figuratively suck the replacement refrigerant in. Lubrication is also added at that time. 

BenT
sent from my electronic leash

> On Jul 28, 2014, at 4:34 PM, Raymond Markett <raym02@yahoo.com> wrote:
> 
> Thanks, how do I get refrigerant in to an empty compressor if it won't spin?
> 
> Sent from my iPhone
> 
>> On Jul 28, 2014, at 3:30 PM, Ben <syncro@GMAIL.COM> wrote:
>> 
>> It will only engage when the system is full of refrigerant. Serves to protect your compressor from spinning without adequate lubrication.
>> 
>> 
>> BenT
>> sent from my electronic leash
>> 
>>> On Jul 28, 2014, at 9:18 AM, Raymond Markett <raym02@YAHOO.COM> wrote:
>>> 
>>> Hi All,
>>> 
>>> Is the 1985 Vanagon A/C clutch supposed to cycle even if the pressure is low? When I turn on my A/C I get voltage on the clutch for about 3 seconds, but the clutch doesn't engage to turn the compressor.  The clutch winding has continuity to ground so it's not open, but it may be shorted. It reads a few ohms. 
>>> 
>>> I know the A/C clutch cycles on my Ford even if the refrigerant is low. Does anyone know if the Vanagon A/C clutch is supposed to cycle on and off even with low refrigerant?
>>> 
>>> Thanks,
>>> 
>>> Raymond
>>> 
>>> Sent from my iPhone