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Dual air compressors control - Printable Version

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+--- Thread: Dual air compressors control (/showthread.php?tid=6971)



Dual air compressors control - Parisjet - 09-10-2022

On my 2005 Newell with dual air compressors pumps, I found yesterday that I had no pressure to open the door. In tracing the issue the compressors were not running. I have done the following and am not sure where to look next.
so the question is what controls the compressors? pressure switch or a series of switches?



RE: Vacuum pump control - Richard - 09-10-2022

You might want to edit your post and retitle the subject line. Those are air compressors and not vacuum pumps.

They are pressure switch controlled.


RE: Dual air compressors control - johnkosir - 09-10-2022

I think your compressors are controlled by a silverleaf controller


RE: Dual air compressors control - Parisjet - 09-11-2022

I will check the pressure switch and see if it is still working, Is it a high pressure closes the loop or opens loop? Is there a pressure tank somewhere in the coach?


RE: Dual air compressors control - hypoxia - 09-11-2022

I can only speak of my 2014. The compressors are 120 VAC with a pressure transducer to sense the pressure. it is mounted on the same block as the pressure gauge. I have not opened the Valid box to see if the transducer is connected to a relay or an electronic switch. Hopefully it's a relay. If the compressors are not starting and have 120 VAC going into the Valid control the problem must be the Valid box. Call Valid, they were helpful when I spoke with them a few years ago. If you can get them to send a schematic of the Valid control box there are probably a bunch of us that would like to see that.

Oddly enough, after your post yesterday I unplugged the pressure transducer to look at the wiring then plugged it in again. This morning the bedroom door would not open & I had to use open the isolation valve to open it. I turned the compressor off & back on and it has worked OK all day. It had not started all night and the tank was empty.

I made some drawings of my coach air system but it is not complete. I'll be at my stick house tomorrow and will have better capabilities to work on that.


RE: Dual air compressors control - Parisjet - 09-12-2022

Just got off the phone with Newell. apparently the box that controls the Air Compressors is made by Siemens and they have changed from that system. By screen on that small green box is blank and there is a fuse behind a wood panel in that compartment that I need to check. hopefully it is only a fuse that blew.


RE: Dual air compressors control - Parisjet - 09-13-2022

I learned a lot about this system yesterday while fault tracing my compressor not coming on. I had checked everything i could think of. I had line voltage at the control box in the compressor bay as well as low voltage (34vdc) but no power to the compressors. My coach is plugged into shore power 50Amp and all of the other electrics were working normal. My switch in the galley will turn off the power to the compressor control box (where the #1 & #2 priority switch is located)
I then noticed that the screen on the Siemens small green box was blank. Just on a lark, since i had spent hours checking everything else, I thought I will try starting the coach and just see what happens. When I turned the ignition key I got nothing, chassis batteries were totally discharged. I then flipped the emergency switch on and the lights came on the dash and to my surprise the compressors started running. I looked in the compressor bay and the screen on the Siemens box was lit. so here is the takeaway on how the system is wired.

The Siemens box controls the compressor circuit and according to the factory it controls the pressure low-on / high-off . The Siemens box gets its power from the chassis battery and not the coach battery or the inverter or the shore power.
You must have a good chassis battery for the compressor (control circuit) to operate.
The power for the compressor can come from the shore power or the coach batteries via the inverter.
My compressor 120v switch in the galley turns the compressor on/off, it will not run with the switch turned off.
I am adding a battery minder charger today to make sure that the chassis battery is fully charged. I can keep it charged with the emergency switch but have heard that this isn't a great idea long term on battery life.
usually there is a fault trace diagram that would have made this easy to diagnose, I may have to draw one up and post here. It would have saved me at least 3 hours of fault tracing without a diagram. The top line would go like this.