Well, kinda stumped. Having issues with my setup. Here is what’s going on.

My compressor was turning on regularly. And one day didn’t make any pressure (30psi). So figured the head got burnt up. No biggie, got a spare.

So I swapped my compressor with a brand new one, and it makes 70psi, and that’s it.

Here is setup.

Viair 444c/400c (swapped 444 for 400)
5 gal (gauge, solenoid, 2 plugged, drain, comp in, and 150psi switch) 13.8v/12.2 (truck running/off)
SMC 15mm orifice 1/2" solenoid

No leaks (everything is sealed with tape and sealant)

My comp kept kicking in due to a failed check (on pump hose), and pressure from tank was slowly bleeding through pump

Any idea why it won’t make pressure? Any adjustments between pump/motor? Changed the intake filter

Tested 444c direct to deadweight gauge. Almost instantly made 200psi. But did slowly bleed through check. I’ll pressure test whole system tomorrow again. But it worked great for 8 months

My first guess is the check valve. There’s been a lot of similar stories and most times it’s been the valve. The leak you noticed on the 444c is a good indicator. They have a habit of gumming up so either they won’t let air through or they’ll leak. Either way, try swapping that out before buying a new compressor or anything.

pressure switch also?

Well. I tested the whole skid this morning, and it works fine. Not sure what it’s problem was, but the 400c runs fine with no leaks. I’ll assume the 444c is just the bad check.

Once in a while, it doesnt make pressure (gets stuck at say 80, or 110 etc), and just runs hot. If I let it cool down, say for 20 mins, and turn it back on, it tops up quickly. Very odd, and much different then my 444

Do live where moisture could freeze in the pressure switch causing it to act up?

I do have some moisture, and freezing is definitly an issue, but I dont think its the PS. Due to the fact that the compressor will run for 10 mins straight, and be stuck at 80PSI/100PSI whatever, if it was the PS, it would be on/off.

Can’t argue with that.

Sounds like a check valve issue since it’s intermittently not building pressure.
Maybe water intermittenly freezes in the check valve.

When you’re letting the compressor cool down for 20 min, keep in mind that the check valve might be thawing out from the heat. Maybe, IDK - just an idea.

I would definitely drain your tank on a regular basis due to being in a freeze zone. It does sound as though the check valve could have been too tight or bad all together. I would also suggest to never run the compressor while the vehicle is OFF.