Trailer air supply not holding

Good Morning folks.

I am having an issue withTrailer air supply not holding brakes (red valve).

The trailer brakes are in adjustment and the trailer dolly brakes works and holds brakes perfectly.

Tried removing red airline and that didn't work, trailer brakes were not holding.

I am not able to adjust tandems since i have air sliding tandems. Traler dolly brakes will not work with red valve pulled out.

There was no issue on last trip, trailer has sat for a week and just noticed the problem today.

Any suggestions would be greatly appreciated.

 

It's 15 and feels like 3

 

I will try that, hope it works.

Thanks

 

Just had roadside fix it.
It was a frozen valve.
He tourced it and it worked.

The receiver was gonna reject load without tandems moved back and it's a penske trailer so they came out and fixed it.

 

Is it gonna freeze again?
What preventive mesures can i take to avoid it.

I will drain the tanks.

 

U r a very knowledgeable person.
Thank you