Purge valve cycling between 125-120 psi every few seconds

if its was frozen and needed the antifreeze it isn't getting rid of the moisture, change the dessicant cartridge.

 

I'm cheap and lazy. I'd just swap out the whole thing for an aftermarket $150-$200. The Bendix is nice if you wanted to service it:

[h=1]Bendix AD-9 Air Dryers[/h] [h=2]Extended Maintenance Intervals[/h] Bendix AD-9 air dryers have a large capacity desiccant cartridge that allows for longer maintenance intervals. Air dryer rebuilds can be stretched to every 36 months when the AD-9 is installed on a typical over-the-road truck or tractor.
[h=2]Easy To Service[/h] Desiccant cartridge replacement is the only reason to ever completely disassemble the Bendix AD-9 air dryer. The check valve, turbo cut-off valve, heater, and purge valve assembly can all be serviced without disassembling the air dryer.

 

Is it used, needing a new desiccant cartridge as well?

 

Fell off the truck? What, is it being shipped in from Jersey?