[Wanderman]

So I noticed with the advent of col weather that my RED gauge needle is dropping down to 60  and the compressor turns on to refill...

What systems affect the red line??

Thanks!

[Fulltiming]

The red needle should be the 'primary' brakes or the rear brakes, the white needle should be the 'secondary' or front brakes. The red needle dropping out prior to the white needle would indicate a leak in the rear brake air tank (2 tanks are located aft of the generator on my coach, the one on top and to the rear is the rear brake air tank, the one lower and toward the front is the front brake air tank) or in the air lines connecting the the rear brakes, OR if the AUX tank is dropping out faster or at the same rate as the red needle on the brake air pressure gauge, the check valve located at the air inlet to the primary brake tank may be defective allowing air to flow out of the brake tank as it leaks out of the AUX air system.

[Wanderman]

OK I will check the fittings. Likely there is a slow leak in one due to shrinkage from the cold.

I am a bit confused though... how do I tell if the aux tank is dropping first... I don't remember a gauge for that...just Supply and brake.

Thank you!

[Richard]

You have two gauges, and three indicators. The two needles on the Brake gauge are for the primary and secondary tanks. The Supply gauge is for the auxiliary system.

[Wanderman]

Ahh the supply gauge stays very stable... just the red indicator slowly drops and triggers the 120v compressor. I am just trying to narrow it down for troubleshoooting/location of the leak. It take about an hour or 2 to leak down enough to trigger the compressor. ~60psi

[Richard]

Well something is amiss. The 120 shouod be triggered off the supply pressure. And if the brake tank pressure is dropping, then the supply pressure should drop to replenish the brake pressure. Michael has posted a series of videos explaining the workings of your air system. I am remote or i would imbed the link for you. The videos will help you noodle this out.

[Fulltiming]

Rick, there are two series of video of presentations I posted on Youtube. The one Richard is referring to is Air System Fundamentals (6-part series). The first two in the series are the most apropos to the issue at hand but I would recommend the entire series. https://www.youtube.com/playlist?list=PL...LLa2eq1PbT should get you the entire playlist. The first two, Introduction and Air Brakes are listed below.

https://www.youtube.com/watch?v=7rnRcyW96m4
https://www.youtube.com/watch?v=pRS8gEyrLyM