engine fan runs constant

Anybody have leads to why? I did put air to the fan solenoid and it kicks in. It’s in a Detroit dd16 westernstar, not sure what else to look into!! Again the engine fan just stays on all the time! I don’t notice any air leaking?

 

i will have to check this tomorrow. Once I
The truck is shut off it takes awhile for the fan solenoid to release air so I can spin the fan by hand but once it gets locked in. Ya u can’t. And the a/c isn’t working on it right now but be a little low on Freon so I’m thinking they could be it but don’t wanna fill it up until have the parts.

 

The thing is the AC is not working right now I’m waiting on the expansion valve part to come in to replace it but it might be a little low on Freon at like 2 pounds. Also, I had switched out the trinary switch that replaces the high, low pressure, but still no power going to the
Compressor

 

To what I found the air once it’s released from the fan, and then the fan stops moving

 

I pulled the electrical plug off the fan solenoid and it wouldn’t release the air or apply the air by plug it back in. I can spin the fan until the fan solenoid kicks it in then locks it up. Compare to when I pull off the electrical connection.