AC compressor clutch not engaging

[jfnar]

I don't know the compressor type. Full disclosure; this is not on a gm truck. It's on a foreign made tractor but I was hoping the function was the same. I'm dealing with this as I recover from covid. I'll get info on the compressor when I get a chance. I went to check the connections and when I started it up the compressor was spinning and the ac was blowing cool. I started doing some work and after about 20 minutes I noticed the air wasn't as cool so I popped the hood and the compressor was spinning but it looked to be turning at about half speed. I'm going to do more research to see if the clutch can be replaced or repaired. Thanks again for the help.

PS: The compressor is Valeo DKV11C .