VNL - D16 Engine Fan Sensor not closing

Good evening all,
I hope someone on here have experienced this same issue i'm having to hopefully tell me how you fix it or what to look for. About a week ago I put my truck in a shop in Phoenix, AZ "Vazquez Diesel" they removed my fan clutch and replaced a broken brass fitting for the air line then put the fan clutch back up. Everything worked fine then 24 hours later my engine fan solenoid will not closed and was constantly dumping air when the truck is on. I replaced the solenoid and it worked good for 2 days and it started again, the new solenoid will not closed just dumping air when the key is on or the trucks running like the old one was doing. when I disconnect the harness the solenoid will close and the air leak will stop then engine fan will move to the highest speed, and when I put the harness back on it the solenoid will open again and the fan speed will drop to medium or normal "i guess". I checked voltage at the harness and its getting 12 volts. I checked the fan clutch and it's working fine, when the key is off the fan will not turn but when I turn the key on the fan moves freely. Any idea where to look or what to check? thanks in advance for any help!

 

Thanks Dave, the air is not leaking from any fitting or line. It's leaking from the air outlet on the solenoid. The solenoid is suppose to open and close but the problem is the solenoid immediately opens when i turn key on and stay open letting air out till i turn the key off, then the solenoid close and air will stop coming out. The solenoid stays open and the engine fan doesn't go off is constantly running.

 

Thanks Nasriza, it is likely that I mixed them up. I will switch them then post the results.

 

I switched the air lines on the solenoid and it got worse, it was just leaking air from the solenoid exhaust with the key on or off so I switch it back. I'm wondering if the new solenoid is also bad. Because the reason why I changed the old one was due to the same thing and the new solenoid worked good for two days and started to dump air from it's exhaust when the key is on. But this all started after the work was done on my fan hub just don't understand it.

 

They remove the fan and replaced a broken air line brass fitting then put it back on.

 

I will try another new solenoid and post the outcome, thanks!