AC on B2650

[gmbc]

Where is the filter for the B2650 AC system. Mine runs for awihile then clutch kicks in and out. Have had recharge and still does it. Checked above cab as roof blew off and all is clear. Any ideas suggestions please

 

[#40Fan]

I know it doesn't answer the question on the filter, but what is kicking in and out? Blower motor, A/C compressor?