New Job, possible issue with Trainer's truck

I have this new job, local driving, seems perfect so far. I have been in my trainers truck for about 3 days now. He said when I activate the air brake switch for the tractor, to keep my thumb on the trailer air brake switch to prevent that from locking the trailer brakes. I thought this was odd but did it. Later he said when the lever is set to lock the trailer brakes, they won't disengage and the air tank goes empty, it takes a long time to get them disengaged. I asked if there was a malfunction, he said no, the other trucks in the fleet are doing it. Today I was driving, we stopped, I pulled out the tractor air brake, forgetting to put my thumb on the trailer air brake switch and it activated along with the tractor air brakes. Sure enough we lost pressure, the trailer brakes would not disengage and he got annoyed. I suggested assertively that there was some kind of malfunction with the brakes, perhaps the lines were crossed. He insists that is not the case. I noticed later the lines behind the cab are both black instead of red and blue. At the end of the hoses that connect to the trailer there is a plastic handle on each hose, one is very faded blue the other faded red. Where the hoses connect to the tractor, there is no color indication, they just screw into these pipes. I am quite convinced these lines are crossed but am in a tough spot. What do you think the issue could be?

 

The trailer is a tanker, we are hauling non pressurized liquid nitrogen fertilizer. I don't want to cause an issue with my trainer or this job, the truck seems to operate ok otherwise. I do notice that the brakes when I apply the brake pedal the brakes are extremely grabby, a slight pressure causes the brakes to engage very hard. This is slowly driving me nuts, something is wrong. I asked him if he does a tug test each moring as I have not been present when he does the pre trip,and he says yes it passes the tug test.

 

I don't hear any air leaks. As long as the trailer brakes are not activated, the air pressure is strong.

 

Yes we are pulling the same trailer. If we activate the trailer brake switch, the brakes he says engage, but then they won't disengage and the tank goes to near zero and takes minutes to fill up again.

 

The air in the tanks start off strong, you engage the trailer brakes, I don't know what happens to the air then, you release the trailer brakes and when looking at the gauge the air is gone and the trailer brakes are not quite locked but have resistance.

 

Well this trailer has air suspension at the tandems, maybe the tractor itself. Still this series of symptoms does not seem right at all.