Yesterday, 04:38 PM
On my coach, this is the behavior of my Thomas compressor and engine driven compressor.
First of all, the pressure gauge at the Thomas compressor always reads 14 psi higher than the Aux digital gauge on the dash. Not sure if one is just inaccurate or something else explains this. I think they should read the same, but they never do.
With the engine not running, the Thomas compressor will cycle on when the pressure gauge at the compressor falls to 112 psi, the dash gauge reads 98 psi. It will run until pressure reaches 125 psi, the dash gauge reads 111.
With the engine running, the engine compressor will cycle on when the pressure(s) falls to 100 psi according to the dash gauge. The three dash gauges are usually pretty much equal between the Front, Rear and Aux. I assume that the pressure protection valves are open between the three tanks and therefore they should be equal. Since the dash gauge reads 100 psi, the gauge at the Thomas compressor reads 114 psi., which is still 2 psi higher than the 112 psi. This being the case, the Thomas compressor will not cycle on. The engine compressor will run until the dash gauges reach 120 psi. The Thomas gauge will now read 134 psi. So by design, I think the engine compressor is handling all of the air needs. The Thomas compressor should not run while the engine is running. On my coach, I think this is the case.
On my coach, the Thomas compressor will not supply any air to the front and rear brake tanks. It only provides air to the Accessory and Leveling tanks. If you are parked with the engine off and have leaks in the brake tanks/lines/fittings, they will eventually leak to zero.
Finally, if you have shop air this is the best source for troubleshooting as it provides air to all tanks. It also allows you to hear major leaks since the engine and Thomas compressor are not running. For small leaks, an ultrasonic tester is required. I found the most leaks in the rear passenger side bay that houses all the Valid leveling and tag axle solenoids.
First of all, the pressure gauge at the Thomas compressor always reads 14 psi higher than the Aux digital gauge on the dash. Not sure if one is just inaccurate or something else explains this. I think they should read the same, but they never do.
With the engine not running, the Thomas compressor will cycle on when the pressure gauge at the compressor falls to 112 psi, the dash gauge reads 98 psi. It will run until pressure reaches 125 psi, the dash gauge reads 111.
With the engine running, the engine compressor will cycle on when the pressure(s) falls to 100 psi according to the dash gauge. The three dash gauges are usually pretty much equal between the Front, Rear and Aux. I assume that the pressure protection valves are open between the three tanks and therefore they should be equal. Since the dash gauge reads 100 psi, the gauge at the Thomas compressor reads 114 psi., which is still 2 psi higher than the 112 psi. This being the case, the Thomas compressor will not cycle on. The engine compressor will run until the dash gauges reach 120 psi. The Thomas gauge will now read 134 psi. So by design, I think the engine compressor is handling all of the air needs. The Thomas compressor should not run while the engine is running. On my coach, I think this is the case.
On my coach, the Thomas compressor will not supply any air to the front and rear brake tanks. It only provides air to the Accessory and Leveling tanks. If you are parked with the engine off and have leaks in the brake tanks/lines/fittings, they will eventually leak to zero.
Finally, if you have shop air this is the best source for troubleshooting as it provides air to all tanks. It also allows you to hear major leaks since the engine and Thomas compressor are not running. For small leaks, an ultrasonic tester is required. I found the most leaks in the rear passenger side bay that houses all the Valid leveling and tag axle solenoids.
Rob
2016 Newell #1536