[Archived]

The specs don’t make sense. The current draw on the greater rated HP compressor is less than that of the compressor with half the HP.

So my first reaction would be to apply the sniff test to the other claims. Usually when a company is willing to mislead on one piece of data, the rest of the data is suspect.

Having said that however, my brain would put a purchasing decision on the back burner until I had the coach relatively leak free. When an aux compressor wears out it usually is due to excessive running. It did not state what the duty cycle was on the compressors being considered, but it is not unusual if the leaks are large to exceed the rating and significantly shorten the life of the compressor. The engine compressor is more robust, but it has a 25% duty cycle so keeping the coach pneumatic system relatively leak free pays dividends.

[Archived]

I will repeat what Jon says …

my brain would put a purchasing decision on the back burner until I had the coach relatively leak free. When an aux compressor wears out it usually is due to excessive running. It did not state what the duty cycle was on the compressors being considered, but it is not unusual if the leaks are large to exceed the rating and significantly shorten the life of the compressor. The engine compressor is more robust, but it has a 25% duty cycle so keeping the coach pneumatic system relatively leak free pays dividends.

This is a very, very profound statement. New coach owners and those veteran coach owners who find his statement enlightening, this is very important.

[Andy]

My coach did not have an aux air compresor. I installed this one, cheap, 12 VDC, 100% duty cycle. Noise will depend on the mounting.

http://www.amazon.com/gp/product/B000FQ78VI/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I only have about 4 loads on the aux, floor slide, door lock, air horn, one other but, i still need to find some leaks. Mine will run about every 12 hours when parked. It has enough pressure I can re-level but the volumetric flow is low enough it takes a long time to do so.

[jack]

I installed a 100% duty cycle compressor from Viair (12V). It has been flawless. Viair 450c, 150psi, about $200.

http://www.viaircorp.com/

[Corey]

Good advice – thank you.
The new compressor is the final step.
I have already resolved many of the leaks. One of the major leaks was the old compressor,
significant leaks at the head and fittings, which additionally revealed the need
to install a new check valve.

I noticed the non-standard compressor I removed did not have
a pressure switch (on/off) installed, but rather just used the bus pressure
switch. Was this installation
correct? I would feel better if the
compressor also had a pressure switch – at least on the high side.

[jack]

I set mine up with its own pressure switch. You can get them with various on-off pressure settings. I think mine is 85-105 but if never want the option to re-level I’d choose something lower.

[Archived]

the way liberty wired that has its own pressure switch in front run box

[Les]

Graingers has lots of repair parts if the electric motor is good they might have parts for the compressor that might be a better option than replacing and re wiring that area.

[Greg]

I considered fixing the aftermarket compressor, but given how noisey it is, and its low output, I think a new compressor is the best option.

I would have rebuilt the orighinal GAST compressor, but it was long gone before I bought the bus. Oh well …

[jack]

It really surprises me that they would wire it off a 220v circuit.

[jack]

it’s 120v

[Archived]

My mistake, I thought it was 220 volts. The compressor I just removed has this type of plug:

I will get my Fluke meter out and see what is going on.

[Archived]

Eric, when you test you should find that twistlock plug is 120v. The twist just keeps it plugged in.

I’m in the same place as you, compressor-wise. The Jun-Air (now Gast, I guess) compressor was removed from my bus before I got it. That California Air model you mentioned has been in my cart in Amazon for months. It is well reviewed and supposedly very quiet. I only need aux air to operate my entrance door while parked so it hasn’t been a high priority. I get about 20 cycles before we have to start pushing it manually.

Why does anyone need to re-level while parked? If the coach is leveled and the leveling system is shut off, doesn’t it just hold air unless the bags themselves are leaking? Either I’m lucky or I never stay in the same place long enough to have to re-level.

[Eric]

Bryan.

You hit a sore spot with the question about re-leveling. I am not familiar with MCI so I cannot draw a comparison, but I can tell you that as Prevost has evolved an 8 air bag suspension has gotten increasingly complex. The basic underlying principle of the system remains but even that has changed over the years.

Our first coach had 8 air bags, three ride height valves and about 8 Prevost installed Norgren valves to control the ride height or leveling. All fittings were compression.

Fast forward to today……….The coach now has more Norgren valves, each air bag location also has a ping tank, and all fittings are push in fittings which age and leak. So because of the changes we not only have almost double the leak points because of the changes to the systems, we have fittings that do have a tendency to leak due to age. At the age of your coach an owner is definitely going to be chasing leaks.

Having said that however once a coach has been made “leak free” by virtue of the replacement of fittings, old valves and old air bags it will have years of leak free service.

[gary]

Yes – you and Jeff are correct. It is 120v.
The unusual plug fooled me. I am
humbled every time I undertake a project.
Thanks to each of you for sharing your knowledge and experience. Even though there is a steep learning curve,
still lots of fun.

Eric