Re: Air brake problem
is it below freezing now?
i'm from michigan, and have learned first hand that when it's cold ice can form inside the air brake system. however, once it's above 32 degrees all your problems should go away. Dissconnecting the main air line from the compressor and filling the line with isopropyl alcohol then re-attaching the line is a great way to remove ice from a line.
if it's been above freezing long enough for everything to thaw then i suspect your problem is unrelated to not draining your tanks. Tanks aren't drained to keep them from freezing, they are drained to remove the buildup of water and ickyness from the system. If a tank is half full and freezes it won't hurt anything. It's unlikely that your tank was full (or even half full for that matter) of water in which case it could burst when froze.
are there any air leaks? does the pressure gauge move at all? Is the compressor turning?
here's something you could try if it's warm enough outside that you've ruled out ice still being in the system. If you have access to a 110 volt air compressor and can bring it to the bus: use a wrench to remove the drain valve from one of your tanks. The fittings will be NPT, most likely 1/4". install in it's place a fitting that allows you to connect your 110v air compressor to the tank. Let it build up pressure.....maybe up to about 80 psi. now shut off the 110v compressor, then go start the bus and see if the air pressure increases. You can throttle the bus up a bit with your foot...if your compressor works it'll build pressure faster when the engine is turning more rpm's. You can step on the brakes a few times which should make your pressure gauge fall...then see if the bus builds any pressure on it's own.
if after all that your bus doesn't increase the air pressure, then i would assume there is a problem with the compressor...perhaps in the regulator.
Quis custodiet ipsos custodes (who will watch the watchmen?)