So my airhorn doesn't work. Has power to it but the compressor won't turn on. I'm at a loss to understand how it all works as well as the only connections are on the solenoid nothing on the compressor. So what tells the compressor to turn on if they aren't attached and where does it get its power? Anyways, the solenoid is bad. All corroded inside, is there a way to test the compressor with out it? Hate to spend money on a new solenoid if I need an entire new set up. If that is the case what have others used and would you use it again?

The horn systems vary like everything else on Barth coaches.

Mine originally had a vacuum driven compressor which was supposed to run whenever the engine had vacuum. The engine vacuum feeds to a large rubber diaphragm which is connected to a small piston that produced pressure.

The pressure line was connected to a small (about 1 quart) steel tank to store pressurized air. This in turn was connected to the solenoid. The wires tripped the solenoid to supply air to the horns.

The compressor and tank were mounted behind the bumper on the driver's side.

That said, NOTHING worked. The compressor was seized up. The solenoid was stuck, and the air horns were plugged with insects and dirt.

I first used a regular shop compressor to test the horns. They run on about 100 psi normally. After a couple seconds of loud hissing, a cloud of dirt and bugs blew out and the horns sounded, pretty loudly.

I replaced the solenoid. Since I had already installed an onboard air system for filling tag axle air bags and tires, I hooked into that system for an air supply and the horns now work.

Here is info on the air system:

https://www.barthmobile.com/eve...383909277#2383909277

I'm not sure what your system is, hopefully this will help.

That explains it. I wondered why there was a "return" vac line running to the compressor but nothing that would make it fire. Did you take the compressor apart to see if you could rebuild it?

Due to noise, the PO relocated my compressor to a rear open compartment where the vacuum pump lived. Because I have a free-standing oil cooler (and needed to power its fan), I decided to install a 6-spot fuse block, powered by a relay engaged by the ignition and directly wired to the nearby engine battery.

Subsequently, I had an external transmission cooler installed, so now that fuse block powers the 2 cooler fans, the air compressor, and the vacuum pump. It's much more efficient than having individual wires to the ignition relay at the front of the coach.

quote:

Originally posted by benebob:
That explains it. I wondered why there was a "return" vac line running to the compressor but nothing that would make it fire. Did you take the compressor apart to see if you could rebuild it?

I did. I figured someone (like you) might want it but vacuum diaphragm was brittle and cracked, the piston O-ring seal was cracked, and more important the die cast metal cylinder bore was really corroded. The rubber parts may be available (I doubt it but maybe) but the main casting was all crusty inside. Too bad.

Yours may be in better shape. Just remove the screws around the outer ring, open it up. There is a spring, diaphragm, piston and a poppet valve inside. If you are lucky you may be able to free them up and restore function. good luck.

Took it apart today and everything is in great shape aside from the filter by the vent (gotta love vehicles from the west). Cleaned it all up and still doesn't work. Maybe I can't make enough vacuum by sucking on it.

It takes a fair amount of vacuum to run it. As you can see there is a flip flop valve that toggles while operating.

Engine vacuum draws the diaphragm against the spring and draws outside air into the piston. When the diaphragm bottoms, the valve flips and dumps the vacuum. The spring forces the piston in and compresses the air in the piston and then out to the tank. Then vacuum valve opens again and the process repeats.

Makes rattling noise when running. good luck.

So looks like the horns are operated by the small compressor on the pass side of engine by? Does it store the air pressure somewhere else? I also have the vacuum pump and tank but don't see the it works the horns but just the air ride?

Actually that is a separate compressor dedicated to the tag axle air bags. Passenger side in front of the radiator, with a belt? About 50 psi max for the air bags.



The horn compressor we are discussing is on the opposite side, below the radiator. The horns require 100+ psi to operate.

Okay thanks for the info. All this fancy equipment is first for us lol. One other question, does anyone know if the air tank is welded to the frame?

quote:

One other question, does anyone know if the air tank is welded to the frame?

Mine isn't; I replaced it, the solenoid valve, and the tubing to the horns.

Steve, is that the pic of the horn compressor from yours? That looks nothing like mine. Will post up pics of mine when i get the chance.

No, that is the compressor for the tag axle air bags.

The vacuum one is round with screws around the perimeter. Tall parts in the middle, side mount flange. Reminds me of a propane regulator. Sorry never took a photo, long gone.

have Barth, will travel