Purge valve keep going off

[JimT]

wow, that IS a crappy place to put something that needs regular service.

Well, if you're holding full air overnight then i guess a general system leak isn't the cause.

I don't see how an air leak (which you say you don't have) could cause water to collect in the tank. Excess humidity and non-functional air dryer would be the top contenders. That and coolant intrusion like Rawze mentioned.

As for the frequent air purge that's either compressor or governor or in between. I would focus on that part of the system. Double check everything is connected and functioning properly. And if you're in a humid area maybe consider replacing the cartridge every 6 months or so. My system says yearly replacement but I like to do mine late fall just before the temp hits freezing and late spring after the "april showers" clear up. I adopted that schedule after one winter where i had a frozen 1/4" air ride supply tube.