1993 nx2000, Air conditioning query

[lovemynx2000]

I have just changed my r12 air conditioner over to the retrokit for a 134a refrigerant. the compressor was completely drained of the r12 oil. all of the refrigerant was drained when i had a new engine dropped in a month ago. i know that when your compressor is drained, and you go to recharge your air conditioner, it wont kick on. I also know that there is a switch that you can manually turn the compressor on. my only question is where is this switch located?